Physiology – hygienic value of basic nutrients of food

PHYSIOLOGY – HYGIENIC VALUE OF BASIC NUTRIENTS OF FOOD. COMPOSITION AND PROPERTIES OF FOOD PRODUCTS.

METHOD OF DETERMINATION AND ESTIMATION OF FOOD STATUS OF MAN

METHOD OF INVESTIGATION OF CASES OF THE FOOD POISONING

Nutrition may be defined as the science of food and its relationship to health. It is concerned primarily with the part played by nutrients in body growth, development and maintenance. The word nutrient or "food factor" is used for specific dietary constituents such as proteins, vitamins and minerals. Dietetics is the practical application of the principles of nutrition; it includes   the planning of meals for the well and the sick. Good nutrition means "maintaining a nutritional status that enables us to grow well and enjoy good health". Maintaining a healthy diet is the practice of making choices about what to eat with the intent of improving or maintaining good health. Usually this involves consuming necessary nutrients by eating the appropriate amounts from all of the food groups. Since human nutrition is complex a healthy diet may vary widely subject to an individual's genetic makeup, environment, and health. For around 20% of the planet's population, lack of food and malnutrition are the main impediments to healthy eating.

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Generally, a healthy diet will include:

1. Sufficient calories to maintain a person's metabolic and activity needs, but not so excessive as to result in fat storage greater than roughly 12% of body mass;

2. Sufficient fat, consisting mostly of mono- and polyunsaturated fats (avoiding saturated and "trans" fats) and with a balance of omega-6 and long-chain omega-3 lipids;

3. Sufficient essential amino acids ("complete protein") to provide cellular replenishment and transport proteins;

4. Essential micronutrients such as vitamins and certain minerals.

5. Avoiding directly poisonous (e.g. heavy metals) and carcinogenic (e.g. benzene) substances;

6. Avoiding foods contaminated by human pathogens (e.g. e. coli, tapeworm eggs);

7. Avoiding chronic high doses of certain foods that are benign or beneficial in small or occasional doses, such as

• foods or substances with directly toxic properties at high chronic doses (e.g. ethyl alcohol, Vitamin A);

• foods that may interfere at high doses with other body processes (e.g. table salt);

• Foods that may burden or exhaust normal functions (e.g. refined carbohydrates without adequate dietary fiber).

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The Food Guide Pyramid

Good nutrition is important for everyone.

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The Food Guide Pyramid lists a range for number of servings in each of five food groups based on age, sex, and level of activity. Serving sizes are also specifically defined. Use the pyramid as an outline of what to eat each day.

 

The small tip of the pyramid includes tats, oils, and sweets. These are foods such as salad dressing and cooking oils, butter and margarine, sugar, soft drinks, candy, and most dessert foods. Foods in this section of the pyramid provide calories but have very little nutritional value. Use them sparingly. The next level of the pyramid contains two food groups that are predominantly animal products. Included in this section are milk, yogurt, cheese, meat, poultry, fish, dry beans, eggs, nuts, and nut butters. These roods are important for the protein, calcium, iron, and zinc they contribute to your diet. Choose skim or low-fat dairy products whenever possible, Select lean cuts of meat and poultry without skin and prepare them without added tat Wits, seeds, and nut butters are high in fat, so eat them in moderation. Vegetarians must to pay particular1 attention to eating a wide variety of non-animal protein foods to ensure a healthful diet.

The third level or the pyramid includes fruits and vegetables. Most people need to eat more of these foods for the abundance of vitamins, minerals, and fiber they supply. Plain varieties of frozen fruits and vegetables offer nutrition similar to that of fresh produce. Avoid canned or frozen fruits in heavy syrups or vegetables in cream sauce unless you can afford the extra fat and calories they provide.

The base of the pyramid includes breads, cereals, rice, and pasta – all foods from the grain group. You should eat more servings from the grain group than any other level of the pyramid. These nutrient-rich foods provide complex carbohydrates, vitamins, minerals, and fiber. Choose at least several servings each day of whole-grain breads and cereals. Remember that starchy foods aren't fattening - unless you top them with butter, cream, cheese, or rich sauces and gravies.

 

Main rules of healthy nutritional

·        Eating fruits, vegetables, and grain products that contain fiber may help prevent heart disease

·        Limiting the amount of saturated fat and cholesterol in your diet may reduce your risk of heart disease

·        Limiting the amount of total fat you eat may help reduce your risk for cancer

·        Eating fiber-containing grain products, fruits, and vegetables may help prevent cancer

·        Eating fruits and vegetables that are "low in fat" and "good sources" of dietary fiber, vitamin A, or vitamin C may help prevent cancer

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CLASSIFICATION OF FOODS

There are many ways of classifying foods:

1. Classification by predominant functions:

(1)Energy-giving foods. These constitute fats and carbohydrates. They are also called protein sparers. Proteins also produce energy to some extent. Cereals, roots and tubers, dried fruits, sugars and fats belong to this group. They supply heat and energy to the body.

(2)Body building foods. These are foods rich in proteins, mineral salts and water. Milk, meat, fish, pulses, oilseeds and nuts fall in this category.

(3)Protective foods. These constitute inorganic salts, vitamins and minerals. They include proteins and water. Milk, eggs, liver, green leafy vegetables and fruits are included in this group. They build our bones, teeth, muscles, soft tissues, blood and other body fluids. They provide material for repair in the body as wear and tear goes on constant-

2. Classification by origin:

1)         Foods of animal origin

2)         Foods of vegetable origin

3. Classification by chemical composition:

1)         Proteins

2)         Fats

3)         Carbohydrates

4)         Vitamins

5)         Minerals

4. Classification by nutritive value:

1)         Cereals and millets

2)         Pulses (legumes)

3)         Vegetables

4)         Nuts and oilseeds

5)         Fruits

6)         Animal foods

7)         Fats and oils

8)         Sugar and jaggery

9)         Condiments and spices

10)    Miscellaneous foods

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Achieving a healthy diet is popularly misperceived as being attainable by eating 'healthy foods'. Many people^[ falsely believe that there are 'good' and 'bad' foods; they develop bad diets because they think that abundant eating of foods they consider 'healthy' will create a healthy diet. However, this is far from the truth.

The consumption of nothing but substances that are deemed healthy, such as an "all-grain diet" or a diet consisting only of pasta or other health-foods, would most likely result in deficiencies because important nutrients (like protein-based foods) would be missed. Foods such as grains, fish, corn, etc. are healthy when consumed with a balanced diet, because in combination they supply us with all of the required nutrients. The most important aspect of any diet is maintaining a healthy intake and balance of foods.

The balance of micronutrients gained from meat, vegetables, and other foods is what makes diets healthy, not only consuming 'healthy' foods. For instance, milk, cheese, and other dairy products are known to have a relatively high fat content. Removing such dairy products from a diet may lower fat ingestion, but it will also negatively affect the intake of calcium and riboflavin that such foods offer.

The basis of all vital processes of an organism of the man is a constant metabolism between an organism and environment. From an environment the man consumes oxygen, water and food-stuff. The role of nutrition consists in updating energy and fabric elements necessary for correct body growth, developments and functioning of an organism, for maintenance of metabolic processes, normal condition of health and working capacity. The full value of a diet of the people is the important factor, which determines their condition of health, influence on body growth and physical development, working capacity, adaptation opportunity, morbidity and life duration. Just due to the nutrition the continuity of a course of two opposite and mutually connected processes of assimilation and dissimilation is provided.

Kinds of food. In various historical times structure of nutrition and character of a nutrition changed depending on development of industrial forces of a society, climate-geographical conditions, direction of economic activity and so on. The character of nutrition of the population was formed gradually depending on an economic and cultural level of development of the country, in view of national customs and features.

Changing concepts

Through centuries, food has been recognized as important for human beings in health and disease. The history of man has been to a large extent  struggle to obtain food. Until the turn of the 19^th century the science  of nutrition had a limited range. Protein, carbohydrate and fat had been recognized early in the 19^th century as energy-yielding foods and much    attention was paid to their metabolism  and  contribution to energy requirements. The discovery of vitamins at the turn of the 20th century “rediscovered" the science of nutrition. Between the two World Wars, research on protein gained   momentum. By about 1950, all the vitamins and essential amino acids had been discovered. Nutrition gained recognition as a scientific discipline, with roots in physiology and biochemistry. In fact nutrition was regarded as a branch of physiology.

Great advances have been made during the past 50 years in knowledge of nutrition and in the practical application af that  knowledge.   Specific   nutritional diseases were identified and technologies developed to control them, as for example, protein energy malnutrition, endemic goitre, nutritional anaemia, nutritional blindness and diarrhoeal diseases.

RELATION OF NUTRITION TO HEALTH

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Good nutrition is a basic component of health. The relation of nutrition to health may be seen from the following view points:

Growth and development: Good nutrition is essential for the attainment of normal growth and development. Not only physical growth and development, but also the intellectual development, learning and behaviour are affected by malnutrition. Malnutrition during pregnancy may affect the foetus resulting in still-birth, premature birth and "small-for dates" babies. Malnutrition during early childhood delays physical and   mental growth; such children are slow in passing their "milestones", and are slow learners in school. Good nutrition is also essential in adult life for the maintenance of optimum health and efficiency. In short, nutrition affects human health from birth till death.

Specific deficiency: Malnutrition is directly responsible for certain specific nutritional deficiency diseases. The commonly reported ones in India are kwashiorkor, marasmus, blindness due to vitamin A  deficiency, anaemia, beriberi, goitre, etc. Good nutrition therefore   is essential for the prevention of specific nutritional deficiency diseases and promotion of health.

         Resistance to infection:

Malnutrition predisposes to infections like tuberculosis. It also influences the course and out-come of many a clinical disorder. Infection, in turn, may aggravate malnutrition by affecting the food intake, absorption and metabolism.

Mortality and morbidity:

The indirect effects of malnutrition on the community are even more striking - a high general death rate, high infant mortality rate, high sickness rate and a lower Expectation of life. Over-nutrition, which is another form of malnutrition is responsible for obesity, diabetes, hypertension, cardiovascular and renal disease, disorders of the liver and gall bladder. More recent reports suggest that diet perhaps plays an important role in certain types of gastro-intestinal cancers. It is now quite well accepted that diet and certain diseases are interrelated.

   Nutrition as a science can be regarded as the study of six main categories of food components: protein, carbohydrate, fat, minerals, vitamins, and water. The first three categories -protein, carbohydrate, and fat — are the only ones that provide calories. Protein provides 4 Calories/gm, as does carbohydrate. Fat provides slightly more than twice as much — 9 Calories/gm.vitamins and minerals.htm

Although minerals and vitamins provide no calories, they function in the many metabolic processes whereby one obtains and utilizes energy from foods and builds and then maintains body tissues. Minerals also function as vital constituents of many body tissues. Iron is a necessary component of hemo­globin, myoglobin, and the cytochromes, and calcium and fluoride are required for sound teeth and bones.

Water. It is an important constituent of food and in its absence, it is impossible to survive beyond a few days. It forms about 70% of body weight. Even bones contain about 20% of water. Water is necessary to make up the loss caused by its excretion in breath, sweat, urine, faeces, and also to renew all the various fluids and solid organs of the body.

 The amount of water needed by every individual generally varies depending upon the outside temperature or the extent up to which the human body is subjected to the manual labour. This rise of temperature and humidity of air increases the necessity for intake of water. An insufficient intake of water leads to creation of disturbance in circulation, of heat regulation mechanism and the retention of products of metabolism. On the other hand, abundant intake of drinking water promotes  the circulation of fluid and increases the activity of kidneys with free secretion of urine. It is estimated that about 80 oz (2.27 litres) of water enters the body daily as such or as a part of cooked food, beverages etc. Out of which 48-64 oz. (1.37- 1.81 litres) is excreted daily in urine, sweat etc.

Some important uses of water are:

- As a solvent for transportation of nutrients in the body.

- It   helps   regulating   body   temperature through evaporation from lungs and skin.

- As an aid in removing wastes of metabolism in the urine.

- As an aid in functions like osmosis.

 It is possible to allocate five groups of diseases, that is direct or mediate related with a nutrition:

1. Alimentary disease, illness caused by deficiency or surplus of components of nutrition.

2. The secondary illnesses of insufficiency or excessive nutrition, which is developed as complication on a background of wearisome illnesses (surgical, infectious, oncology and others.)

3. Disease of multifactor nature that very much frequently develops on a background of genetic predilection, for example, atherosclerosis, gout, idiopathic hypertensia, oncological diseases etc.  

4. Disease, which are transferred by a nutritional way (some infections and helminths, alimentary poisonings).

5. Alimentary intolerance - atypical reaction to nutrition, for example alimentary allergy, idiosyncrasy.  Fats.

FUNCTIONS OF FOOD:

The main functions of food are:-          

1. Provision of energy - It provides fhe body fuels or energy foods, which on oxidation supply heat and energy. Even while at bed rest, some energy is being expended on respiratory, circulatory, and other body processes.

2. Body building and repair - It provides the material needed for growth  and upkeep of the body. Even after growth isstopped, the body continues to change throughout life. Tissues are continually wearing out and these must be changed or repaired.

3. Maintenance and regulation of tissue functions - It provides the materials which regulate and maintain body functions and processes. They regulate the way, in which various parts of the body act and protect the body from disease

On the basis of the above functions foods have been classified as :

(1) Energy-yielding foods: These are foods rich in carbohydrate and fat, e.g., rice, wheat, potatoes, sugar, fats and oils.

(2) Body building foods: These are foods rich in protein, e.g., milk, eggs, meat, liver, fish, pulses, oilseed cakes.

(3) Protective foods: These are foods rich in vitamins, minerals and proteins, e.g., milk, green leafy vegetables. Protective foods are so called because they protect the body against infection, disease and ill health.

A balanced diet must contain foods from the above three groups.

Balanced diet is one, which will meet a person's caloric need and contain all nutrients, particularly proteins, and vitamins. In addition, the food should satisfy the taste and desire of a person and should have enough roughage to promote the peristalsis. Balanced diet should have 50-60 % carbohydrates 30-35 % fats and 10-15 % proteins with necessary vitamins and minerals.

1. Conformity of entering energy to energy losses.

2. Conformity of chemical structure of alimentary substances to physiological needs of an organism.

3. The maximal variety of a ration.

4. Keeping of an optimum regimen of nutrition.

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NUTRIENTS

Nutrients are organic and inorganic complexes contained in food. There are about 50 different nutrients which are normally supplied through the foods we eat. Each nutrient has specific functions in the body. Most natural foods contain more than one nutrient. These may be divided into :

(i) Macronutrients: These are proteins, fats and carbohydrates which are   often   called   "proximate   principles" because they form the main bulk of food.

 (ii) Micronutrients : These are vitamins and minerals. They are called micronutrients because they are required in small amounts which may vary from a fraction of a milligram to several grams.

A short review of basic facts about these nutrients is given below.

Animal Foods

These are, for example, e.g. meat, fish, eggs milk and milk products.

Meat

Characteristics of Good Meat

1. It has marbelled appearance due to fat and is acidic.

2. It is firm and elastic to touch.

3. No oedema or bad odour.

4. It is dry on surface and does not shrink much on cooking.

Meat of Unsound Quality

1. It is soft, moist and pale.

2. Reaction is alkaline and has putrefied odour.

Following are some of the diseases produced by consumption of unsound meat.

1. Tuberculosis: Tuberculosis is common in cattle but rare in sheep and goats. Usually, lymphatic glands, lungs, and liver are affected, but not the muscles. Howevr, flesh of tubercular animal should always be condemned.

2. Food poisoning may be caused by tinned meat. Such tins should have no dents and their ends should be concave and not convex. On opening, air should rush out and contents should not be discoloured.

3. Cysticercosis: Embryos of tape-worms inhabit the muscle of pigs, ox, etc and such a meat when ingested causes tape worm infection. However, embryos are killed, if such a meat is properly cooked.

4. Trichenella spiralis: Embryos are usually encysted in pig meat.

5. Actinomycosis through ox-meat especially in damp climate. The affected portions should be condemned.

6. Liver flukes is common in liver of sheep. Cooking always kills the parasites.

Preventive Measures

1. Compulsory inspection of animals before slaughtering and also of carcasses by veterinary experts at slaughter houses, which should be public owned.

2. The slaughter houses should be pucca built with proper drainage and free water supply for cleaning. These should be situated away from habitation and no dogs, etc. should be allowed in the vicinity.

3. Persons suffering from infectious diseases should not be al­lowed to handle meat.

4. Meat at shops must be properly protected from flies.

5. Vehicles for transporting meat must be clean.

Fish

It is highly nutritive and easily digested. It contains all vitamins (except Vit. C) and has high calcium value. Its liver is rich in Vit. A and D. Fresh fish has bright pink gills and firm shiny scales with prominent eyes. It is firm and elastic with no bad odour.

Fish is considered as 'brain food'. It contains omegas, a polyun-saturated fatty acid, which lowers blood pressure, relieves arthritis inflammation and aids brain development. Fish oils tend to lower blood cholesterol and triglycerides.

Fish poisoning may occur by toxin produced by Cl. botulinum and decomposed fish may cause protamine poisoning. Shell fish from polluted water contains toxins.

Eggs

An average hen's egg weighs about 60 gms, with 2/3rd as white and 1/3 as yolk. It has all the important nutrients except carbohydrates. The egg white is mostly egg albumin; while the yolk contains fat, lecithin, phosphorus, calcium and iron. The egg can be preserved by making their shells air tight by immersing them in lime-water or by coating them with oil or sodium silicate a process of glazing. The test for freshness of an egg: put it in 10% common salt solution; good eggs sink while stale ones will float.

Milk

It is an ideal food containing nearly all the nutrients of well balanced diet. It is the best particularly for infants, children, and lactating mothers. It contains milk sugar (Lactose), proteins, fat, vitamins, clacium pJzosphorus, chloride, potassium and sodium but is poor in iron.

Composition of Milk

In proteins, there is more of caseinogen in cow's and buffalo's milk; while there is more of lactalbumin in human and goat's milk. Fat contents in human and cow's milk are nearly the same, while in goat's and buffallo's milk they are more.

Methods of Preservation of Milk

1. Boiling is very common method in India. It is quite simple and satisfactory as all pathogens are killed.

2. Sterilizationby raising the temperature to 100°C for 15 minutes in a closed sterilised container.

3. Drying: Milk is passed over heated rollers and converted to milk powder. Being easily digestable, it is an ideal baby-food. But now this milk powder as baby food is being condemned.

4. Condensed milk: Milk is gradually heated under pressure to reduce water contents to about 1 /4th of its original volume and then packed in sealed tin. The varieties are full cream or skimmed milk both in sweetened and unsweetened forms.

5. Addition of antiseptic e.g., boric acid, sulphurous acid, N202. This is however not used in practice.

6. Pasteurisation is the best and most successful practical method, as it ensures destruction of pathogenic organisms by heat without altering the physical character of the milk.

Pasteurisation

The milk is heated to 145°-150°F, for half an hour and then rapidly cooled to 55°F. This retains the enzymes, taste, flavour and nutrients of milk. The milk is kept free of contamination from the time of heating till its delivery to consumers. Two common methods of pas­teurisation are:

1. Holder's method: Milk is heated in cylindrical tanks with steam passed in water jackets surrounding it to 145°-150°F for 30 minutes and then cooled rapidity to 55°F by passing cold water through the jackets.

2. Flash method or high temperature short time (H. T.S. T.) method:

Here milk is heated 160⁰-170⁰F for a few seconds and then quickly cooled to 50°F. Holder's method is usually considered more satisfac­tory although H.T.S.T. method is being perfected.

For a satisfactory town milk scheme, the following points should be considered.

1. Improvement of cattle breed, free of diseases.

2. Sanitary cattle sheds with efficient drainage and enough water supply to ensure proper cleaning.

3. Milkmen should be free from infectious diseases and trained to observe scrupulous hygienic precautions while milking and han­dling the milk, which should be in clean containers and protected from flies.

4. The milk should be first chilled, if far away from pasteurisation plants and then transported, pasteurised and sealed in bottles.

5. For practical observance of above mentioned measures, there should be proper legislative control by public health department.

Test for pasteurisation: To test for adequte pasteurisation process, following tests are carried out:

1. Phosffhatase test: Phosphatase (an enzyme) is normally present in milk and is inactivated during pasteurization. The presence of phos-phatase in the milk indicates inadequate pasteurisation. This test is useful in Holder's method but is not so reliable in H.T.S.T. method, in which phosphatase may not be completely inactivated, in spite of efficient pasteurisation.

2. Coliform bacilli test: Coliform bacilli present in milk are destroyed by pasteurisation. Their presence in milk means either inadequate pasteurisation or recon lamination of milk at some later stages.

Milk-borne Diseases

These are tuberculosis, typhoid, paratyphoid, dy sentry, cholera, diphtheria, sore throat and undulant fever, infectious hepatitis, poliomyelitis, etc.

Other Preparations of Milk

Dahi (curd) prepared by boiling, wanning the milk and adding a little curd. The fermentation is by lactic and bulgaris bacilli. It is easily digested.

Butter milk is made by churning curdled milk and removing but­ter.

Butter contains fat (80-90%), lactose, salts, traces of casein and arom-tic principle. It is very nutritious and easily digestible among all fats.

Ghee: It is clarified butter and largely used in tropical countries in preference to butter, as it can be preserved for longer period.

Cheese is a concentrated protein food and has about 30% fat and 28% casein.

Skimmed milk and cream are made with centrifugal machine. Cream is removed and skimmed milk is left over.

Vegetable Foods

These are cereals, pulses, roots, green vegetables, fruits and nuts.

Cereals are mainly carbohydrates and also contain minerals (P, Cal, Mg, K, Fe). Wheat and rice are the main cereals. A good wheat flour must have at least 8% gluten. Usually it has 60-70% car­bohydrates and 10-12% gluten.

Rice is poor in proteins, fat and minerals, but very rich in starch.

Barley is rich in proteins and minerals.

Maize is rich in proteins, carbohydrates and fatty matter.

Oat is rich in protein and carbohydrates.

Bajra is rich in protein and carbohydrates.

Pulses are nitrogenous substances. Vegetable protein is legumin (24-25%). Minerals are potassium, calcium and sulphur. Pulses also contain carbohydrates but are deficient in fats.

Roots and tubers ^.potatoes, beet-roots, carrots etc,

Vegetables arc usually a rich source of minerals and vitamins.

Fruits: These may be food fruits or fruits of flavour fruits.

Flavour fruits e.g., orange, lemon. These quench thirst and are rich in Vit C and minerals.

Nuts like ground nut are very rich in proteins.

In general, vegetable foods form more bulk and have less protein. If proportion of vegetable in food is very high, the bowels get dis­tended and there is more muscular effort on intestine and more blood and energy required for the purpose.

Beverages and condiments are substances which enable food to be taken with pleasure and relish and aid digestion. These are water (universal beverage) tea/ coffee, fermented drinks, spices, etc.

 

Metabolism

It is process of chemical changes occurring in the body after diges­tion and absorption of food nutrients, their utilisation by body tissue, for processes of synthesis (anabolism) and for those of breakdown (catabolism).

Energy for basal metabolism: This is the energy necessary for maintaining body temperature and for activity of heart and vital organs, when body is at complete rest The basal metabolic rate (BMR) of an average adult is 1500-1700 Cal/day and is dependent on body weight, age, sex, state of health, mental state and the environments.

Food Calorie

A calorie is defined as the amount of heat required to raise the temperature of 1 gm of water through 1°C from 14.5°C to 15.5°C.

Unit of Food (Cal.) 1 - 1,000 small calories.

·        1 gm. of carbohydrate produces    4.1 Cal.

·        1 gm. of fat produces             9.3 Cal.

·        1 gm. of protein produces          4.1 Cal.

Family co-efficient: It is relative energy requirement of various members of household in terms of such units expressed as mean value taken as one:

So for adult male unit is            1

For adult female unit is          0.9

For pregnant women unit is      1.2

For nursing mother unit is        1.5

BALANCED DIET

Balanced diet is one, which will meet a person's caloric need and contain all nutrients, particularly proteins, and vitamins. In addition, the food should satisfy the taste and desire of a person and should have enough roughage to promote the peristalsis. Balanced diet should have 50-60% carbohydrates 30-35% f-»ts and 10-15% proteins with necessary vitamins and minerals.

PROTEINS

The word "protein" means that which is of first importance. Indeed they are of the greatest importance in human nutrition. Proteins are composed of carbon, hydrogen, oxygen, nitrogen and sulphur in varying amounts. Some proteins also contain phosphorus and iron and occasionally other elements. Proteins differ from carbohydrate and fat in the respect that they contain nitrogen. Proteins are made up of simpler substances, called amino acids. These are the building blocks of protein.

Some 22 amino acids are stated to be needed by the human body, out of which eight are called "essential". The essential amino acids are: (1) Isoleucine (2) leucine (3) lysine (4) methionine (5) phenylalanine (6) threonine (7) tryptophane; and (8) valine. These are called "essential" because the body cannot synthesize them in sufficient quantity, and therefore they must be obtained from the food we eat.

Functions :

Proteins are needed by the body: -

ü                 For growth and development: They furnish the building material, i.e. the amino   acids  from which  the  body proteins are synthesized.

ü                 For repair of body tissues and their maintenance: It has been shown that the   body   proteins   are   constantly being broken down; they have to be replaced   for   which   fresh   protein intake is required.

ü                 For synthesis of antibodies, enzymes and hormones: Antibodies, enzymes and hormones contain protein. The body   requires   protein   to   produce them.

ü                 Proteins can also furnish energy to the body, but generally the body depends for its energy on carbohydrates and fats rather than proteins.

Sources:

There are two main dietary sources of protein: -

Animal  sources:   milk,   eggs,   meat, fish, etc.

Plant sources: Pulses, cereals, nuts, etc.

A mixed diet containing both animal and vegetable proteins meets with the needs of essential amino acids required by the body. Each gm. of protein on oxidation yields 4.1 calories of heat.

Protein rich foods are milk, lean meat, fish, poultry, eggs, nuts, legumes, beans and pulses.

The protein content of some foods is given in Table 2.

Protein requirements

It is customary to express protein requirements in terms of body weight. Doctors recommended 1,0 g. protein/kg, body weight for an adult. Daily allowances recommended by the ICMR for various population groups are given in Table 16 (see page 113).

Effects of protein deficiency:

The effects of protein deficiency may summarised as below.

During pregnancy: Still  birth,   low birth weight, anaemia

Infancy     and     early     childhood:  Marasmus,     kwashiorkor,     mental retardation,    stunted    growth    and development

Adults: Loss of weight, underweight, poor musculature, anaemia, increased susceptibility to infection, frequent loose stools, general lethargy, incapacity to sustained work, delay in wound healing, cirrhosis of liver, oedema, ascitis, etc.

 

FATS OR HYDROCARBONS.

 Fats are composed chemically of carbon, hydrogen and oxygen, only in different proportion than they are contained in car­bohydrates. There is less of oxygen in fats than in carbohydrates. The true fats are glycerides of fatty acids and butter, ghee, vegetable hydrogenated oil, animal fat etc. are the examples of various fats com­monly used by people. Fats are a form of con­centrated food and like carbohydrates, they are used as body fuels for the production of heat and energy. As fats are not soluble in water, the process of digestion changes the fat into an emulsion form for their ab­sorption into the body. Liquid fats and those which melt at body temperature are somewhat better digested than those which are much harder. A fat-rich diet slows the process of digestion and gives a feeling of heaviness and fulness. In the body, the fat which cannot be immediately used, is partly deposited as adipose tissue under the skin and partly unabsorbed passes out with the faeces. Excessive intake of animal fats increases blood cholesterol level, which may be a contributory factor for the development of heart diseases. Certain unsaturated fatty acids in fats are considered essential for health. Fat soluble vitamins are present in animal fats. Fat diminishes protein metabolism and therefore is called protein sparing food. The daily diet of an adult should include 45 to 60 gms. of fat.

Sterols. These are substances which resemble fats only in their physical properties and solubilities. Ergosterol and cholesterol are the examples of this group and are associated in the body in the bile, nervous tissue and blood corpuscles.

Some fats such as groundnut oil, gingely oil are liquid at  room temperature: some fats such as ghee and butter are solid at room temperature. Fats are again classified into saturated and unsaturated fats. In general, animal fats are "saturated" fats; vegetable oils and fats are "unsaturated" fats. Current researches indicate that excessive intake of saturated  fats (i.e., animal fats) is harmful to the body. Cardiovascular disease which is a frequent disease in the western countries and among the well-to-do people in India is attributed to excessive consumption of saturated fats.

Fats

Most people know that we should be cutting down on fat. But did you know it's even more important to try to replace the saturated fat we eat with unsaturated fat? Read on to find out how.

We need some fat

It's important to have some fat in our diet because fat helps the body absorb some vitamins, it's a good source of energy and a source of the essential fatty acids that the body can't make itself. But having a lot of fat makes it easy to have more energy than we need, which means we might be more likely to put on weight. So if you want to eat healthily and keep a healthy weight, look out for lower fat alternatives wherever possible and try to eat fatty foods only occasionally.

Different sorts of fats

Although it's important to try to eat less fat, we also need to think about the types of fat we are eating. We should be cutting down on food that is high in saturated fat or trans fats or replacing these foods with ones that are high in unsaturated fat instead. We should also be having more omega 3 fatty acids, which are found in oily fish.

Saturated fats

Having too much saturated fat can increase the amount of cholesterol in the blood, which increases the chance of developing heart disease.
These are all high in saturated fat:

·                     meat products, meat pies, sausages

·                     hard cheese

·                     butter and lard

·                     pastry

·                     cakes and biscuits

·                     cream, soured cream and crème fraîche

·                     coconut oil, coconut cream or palm oil

 

Trans fats

Trans fats have a similar effect on blood cholesterol as saturated fats, they raise the type of cholesterol in the blood that increases the risk of heart disease. Some evidence suggests that the effects of these trans fats may be worse than saturated fats. However, most people eat a lot more saturated fat than trans fats. Trans fats can be formed when liquid vegetable oils are turned into solid fats through the process of hydrogenation. Foods containing hydrogenated vegetable oil, which must be listed in the ingredients list on the label, might also contain trans fats. Trans fats are often found in these types of foods:

·                     biscuits and cakes

·                     fast food

·                     pastry

·                     some margarines

These sorts of food are usually high in saturated fat, sugar and salt so if you are trying to eat a healthy diet, you should try to keep these to a minimum. Trans fats are also found naturally at very low levels in foods such as dairy products, beef and lamb.

Unsaturated fats

Unsaturated fats can be a healthy choice. They don't raise cholesterol in the same way as saturated fats. These types of fats provide us with the essential fatty acids that the body needs. These include the unsaturated fats found in oily fish, which may help prevent heart disease. These are all high in unsaturated fat:

·                     oily fish

·                     avocados

·                     nuts and seeds

·                     sunflower, rapeseed and olive oil and spreads

·                     vegetable oils

If you want to make a healthy choice, try to have more unsaturated fats and less saturated fats, this means you could choose:

·                     oily fish instead of sausages or a meat pie

·                     use unsaturated oils such as olive, sunflower or rapeseed oils instead of butter, lard and ghee in cooking

·                     snack on some unsalted nuts instead of a biscuit

·                     make your mashed potato with olive oil and garlic instead of butter and milk for a change

·                     choose a fat spread that is high in unsaturates instead of butter

More on a healthy heart

 

What's a lot and what's a little?

If you want to try to cut down on fat, or you just want to watch how much fat you are eating, you can compare the labels of different food products and choose those with less total fat and less saturated fat. You will see figures for the fat content on many food labels and some foods will also give figures for saturated fat. Use the following as a guide to what is a lot and what is a little fat per 100g food. 20g fat or more per 100g is a lot of fat 5g saturates or more per 100g is a lot 3g fat or less per 100g is a little fat 1g saturates or less per 100g is a little fat If the amount of total fat is between 3g and 20g per 100g, this is a moderate amount of total fat. Between 1g and 5g of saturates is a moderate amount of saturated fat.

Tips for cutting down

Here are some practical suggestions to help you cut down on fat, especially saturated fat:

·                     Choose lean cuts of meat and trim off any visible fat.

·                     Grill, bake, poach or steam rather than frying and roasting so you don't need to add any extra fat.

·                     If you do choose something high in fat such as a meat pie, pick something low fat to go with it to make the meal lower in fat – for example you could have a baked potato instead of chips.

·                     When you're choosing a ready meal or buying another food product, compare the labels so you can pick those with less total fat or less saturated fat.

·                     Put some extra vegetables, beans or lentils in your casseroles and stews and a bit less meat.

·                     Measure oil for cooking with tablespoons rather than pouring it straight from a container.

·                     Have pies with only one crust rather than two – either a lid or a base – because pastry is very high in fat.

·                     When you're making sandwiches, try not using any butter or spread if the filling is moist enough. When you do use fat spread, go for a reduced-fat variety and choose one that is soft straight from the fridge so it's easier to spread thinly.

·                     Choose lower fat versions of dairy foods whenever you can. This means semi-skimmed or skimmed milk, reduced fat yoghurt, lower fat cheeses or very strong tasting cheese so you don't need to use as much.

·                     Instead of cream or soured cream try using yoghurt or fromage frais in recipes.

Omega 3 fatty acids

Oily fish is the best source of omega 3 fatty acids. These fatty acids have been shown to help protect against coronary heart disease.  Some omega 3 fatty acids are found in certain vegetable oils, such as linseed, flaxseed, walnut and rapeseed, but these aren't the same type of fatty acids as those found in fish. Recent evidence suggests that the type of fatty acids found in vegetable sources may not have the same benefits as those in fish.

Functions:

 Fats serve the following functions:

ü      Dietary fat is a concentrated source of energy. One gram of fat supplies 9 calories of energy. This is almost twice the number of calories derived weight for weight, from carbohydrate or protein.

ü      Fats are carriers of fat-soluble vitamins, e.g., vitamins A, D, E and K.

ü      Dietary   fat supplies "essential fatty   acids". Linoleic   acid, one of  the ssential fatty acids, prevents scaly skin formation. In general, essential fatty acids are needed for growth and maintenance of the integrity of the skin.

ü      The fat layer below the skin plays an important role in maintaining our body temperature.

ü      Fats  provide support  for many organs in the body such as heart, kidney, intestine etc.

ü      Foods containing fats are tasty.

Sources:

Dietary fats are derived from two main sources - animal and vegetable sources.

Animal   sources:   These are ghee, butter, fat of meat, fish oils, etc.

Vegetable sources: These are various vegetable oils such as groundnut, gingely, mustard, cottonseed, safflower (kardi) and coconut oil.

CARBOHYDRATES

They form the largest component of diet of most of the people and furnish most of the required energy. Starches and sugars are grpuped under this head. Wheat, rice, maize, barley, cereals, potatoes, sweet potatoes, turnips, root vegetables etc., are rich in starches, while sugarcane, beetroot and fruits contain the sugars. The original source of all starches and sugars is green plants. When plants have excessive sugar and they need to store it, as reserve supply of food, plant body is capable of changing its sugar into starch. Carbohydrates are abundantly present in food. All carbohydrates have to be changed into glucose and fructose before they can be absorbed into the body. 1 gm of sugar yields 4.1 calories of heat. Chemically carbohydrates are composed of carbon, hydrogen and oxygen as the name implies. Polysaccharides are various starches which are converted into two molecules saccharides i.e.> cane sugar, beet sugar, milk sugar and malt sugar. These on further digestion change into single molecule monosaccharides, glucose and fructose. The daily requirement of car­bohydrates varies from 50 to 60% of total energy intake.

The carbohydrates are chief sources of energy. Over half the energy requirements of the body are met with by carbohydrates. In the active muscles, the glacose is oxidised for the production of energy and warmth. Glucose which cannot be used imme­diately, is converted into glycogen and stored in the liver and muscles or converted into fat and stored under the skin.

Sources:

There are three main sources of carbohydrate:

MINERAL SALTS

Vitamins and minerals.

These are essential for the main­tenance and growth of the body. They also maintain the normal osmotic pressure in the fluids and tissues of the body, besides playing an important part in the acid alkali regulation of the body. They are also required to make good the loss of salts excreted in urine and sweat. The alkali forming elements are calcium, potassium, sodium, iron and manganese. The acid forming elements are phosphorus, sulphur and chlorine.

The main functions of salts in the body are:

1.      To maintain tone of muscles, nerves and blood.

2.      To stimulate digestive secretions.

3.      To help general growth of the body.

4.      To    help    in    maintaining    acid    alkali equlilibrium.

5.      To maintain rigid structure of body such as bones, teeth etc.

In the human body there are at least 15-16 dif­ferent mineral elements and each has its own specific part to play.

The following mineral salts are, however, most important from nutrition point of view:

1.                  Calcium. It is the chief constituent of bones and teeth. It gives rigidity, strength to bones and hardness, shine to the teeth. It controls rhythmic activities of the heart and contractile muscles. It is essential for the coagulation of blood. It is required in much greater amount during the periods of pregnancy and lactation. Its daily requirement for an average adult is 1 gm. and for lactating mother 1.5 gms. Calcium metabolism is closely related to phosphorus and vitamin D. Its deficiency leads to poor development  of bones  and  teeth,  rickets,  osteomalacia, delayed blood coagulation, hyperplasia of parathyroid glands and low calcium tetany. The best sources of lime salts are milk, cheese, eggs, dark green leafy vegetables and dried fruits. The calcium of green vegetables is, however, not so easily absorbed as the calcium of milk.

2.                  Phosphorus. It is contained in every cell of the body. It is essential for the multiplication of cells and the growth of body. It works with calcium in bones and teeth. Its daily requirement in the diet is 1.5 gms. but mqre of it is required during pregnancy. Its deficiency is characterised by softening of bones, caries of teeth, stunted growth, changes in the reaction of blood and depression of vital processes. Its chief sources are cheese, yolk of eggs, oatmeal, almonds, nuts, peas, bones, whole wheat, liver, milk, potatoes etc. In cereals about 50 to 80% of phosphorus is present in the form of phytic acid, i.e., inositol hexosephosphoric acid.

3.                  Iron. It is the main constituent of haemoglobin of blood and nuclei of the cells. It acts as an oxygen carrier to the lungs and tissues and plays an important part in the oxidation and catalysis of enzymes. Its daily requirement is 25 mgms. But an adult woman needs more of iron to compensate for loss of blood in menstruation and also during pregnancy, lactation etc. An adult person has about 3-4 gms of iron out of which 2.4-2.7 gms. exist in the form of haemoglobin. Its deficiency causes anaemia. Its chief sources are liver, red meat, eggs, pulses, cereals, onion, green leafy vegetables, dry fruits, dates, figs, resins etc. Human milk contains 1 mg. of iron per litre.'

4. Iodine. It occurs in all the tissues and fluids of the body. It is an essential constituent of thyroid gland. Its iodine rich secretion thyroxin, regulates the metabolism. Its daily requirement is about 150 m.gms. This may be increased during puberty, pregnancy and menopause. Its deficiency causes goitre. Its chief sources are seafish, cod liver oil, yolk of eggs, onions and fresh vegetables. Iodised table salt is used to supply the iodine in endemic goitre areas. The minimum daily requirement of iodine for an adult person is 0.15 mg. to 0.30 mg.

5. Sodium Chloride. It occurs in all the tissues and fluids of the body. It maintains osmotic pressure in blood and other tissue fluids. It is essential for the maintenance of PH ion concentration. It is present in gastric juice and bile. Its daily requirement is 10 to 15 gms. Its deficiency leads to cramps, marked general weakness, mental lassitude, dyspnoea on exertion and heat exhaustion. These symptoms can be delayed or even prevented by drinking of water containing 0.25% of sodium chloride.

6.      Copper.   It   helps   in   the   formation   of haemoglobin of blood along with iron. Its daily requirement is 2 m. gms. for an adult.

7.      Chlorine. It is necessary to maintain the composition of blood and also in the formation of hydrochloric acid in the body. It is found in common salt, bananas, tomatoes, lettuce and green leafy vegetables.

VITAMINS

Vitamin and mineral ABCs

Vitamins and minerals are substances your body needs in small but steady amounts for normal growth, function and health. Together, vitamins and minerals are called micronutrients. Your body can't make most micronutrients, so you must get them from the foods you eat or, in some cases, from supplements.

Vitamins: Partners in regulating body functions

Vitamins are needed for a variety of biologic processes, among them growth, digestion, mental alertness and resistance to infection. They also enable your body to use carbohydrates, fats and proteins, and they act as catalysts — initiating or speeding up chemical reactions. Though vitamins are involved in converting food into energy, they supply no calories.

Vitamins can be either water-soluble or fat-soluble.

Water-soluble vitamins. Vitamin C, biotin and the seven B vitamins — thiamin (B-1), riboflavin (B-2), niacin (B-3), pantothenic acid (B-5), pyridoxine (B-6), folic acid (B-9) and cobalamin (B-12) — dissolve in water (water-soluble) and aren't stored in your body in any significant amounts. Surplus water-soluble vitamins are simply excreted in your urine.

Fat-soluble vitamins. Any extra vitamin A, D, E or K not used by your body right after ingestion is stored in your body fat and liver. Excess fat-soluble vitamins can accumulate in your body and become toxic. You're especially sensitive to excess amounts of vitamins A and D. Because vitamins E and K affect blood clotting, talk with your doctor before taking a supplement that contains either of these vitamins if you're taking a blood thinner, such as warfarin (Coumadin).

Minerals: Building blocks for your body Minerals are the main components in your teeth and bones, and they serve as building blocks for other cells and enzymes. Minerals also help regulate the balance of fluids in your body and control the movement of nerve impulses. Some minerals also help deliver oxygen to cells and help carry away carbon dioxide.

Minerals have two categories:

Major minerals. Calcium, phosphorus, magnesium, sodium, potassium, sulfur and chloride are considered major minerals because adults need them in larger amounts — more than 250 milligrams (mg) a day.

Trace minerals. Chromium, copper, fluoride, iodine, iron, manganese, molybdenum, selenium and zinc are considered trace minerals because your body needs them in smaller amounts — fewer than 20 mg a day.

Whole foods: Your best source of micronutrients

Whole foods are your best sources of vitamins and minerals. They offer three main benefits over supplements:

   Whole foods are complex. They contain a variety of the micronutrients your body needs — not just one. An orange, for example, provides vitamin C but also beta carotene, calcium and other nutrients. A vitamin C supplement lacks these other micronutrients.

Whole foods provide dietary fiber. Fiber is important for digestion and can help prevent certain diseases such as cancer, diabetes and heart disease. Adequate fiber intake can also help prevent constipation.

Whole foods contain other substances that appear to be important for good health. Fruits and vegetables, for example, contain naturally occurring food substances called phytochemicals, which may help protect you against cancer, heart disease, diabetes and high blood pressure. Many are also good sources of antioxidants — substances that slow down oxidation, a natural process that leads to cell and tissue damage. If you depend on supplements rather than eating a variety of whole foods, you miss the potential benefits of these substances.

Rational nutrition and its main principles

Rational nutrition is full in quantity and balanced in quality nutrition pattern for normal height, physical and psychophysiological organism development, its high work capacity, active longevity and adverse environmental natural, man-caused, social environment factors resistance.

The rational nutrition has to follow such basic principles:

1. To be full in quantity. The dietary intake food calorific value must correspond to the organism energy consumption including the undigested part of the dietary intake.

2. To supply the dietary intake quality (balance) which means that all nutrients, proteins, fats (including animal), carbohydrates (including polysaccharides, celluloses, dietary fibers), vitamins, macro- and microelements, flavoring substances must be contained in optimal quantities and ratios.

3. The rational dietary pattern must be followed: food intake hours must correspond to the organism biological rhythms: adults must have 3-4 meals a day and children of different ages - 5-6 meals a day. Intervals between food intakes must be 5-6 hours for adults and 3-4 hours for children. The daily intake distribution must correspond to the organism physiological needs: the breakfast and dinner (the organism physical activity period) must contain 30-35% and 45-50% of the daily intake, the supper (after finishing the active daily period) – 20-25%.

4. Food must be cooked in accordance to the digestive system enzymic abilities. The perfect taste, good nutrition value, easy gastrointestinal digestion and high level of food absorbency must be reached during the food preparation.

5. Food must not be toxic. Products and ready meals must not contain the toxic substances in harmful to the human organism concentrations.

6. Food must be harmless in epidemiological aspect. Products and ready meals must not contain the etiological agents of infectious foodborne diseases - bacteria, viruses, fungi, protozoa, geo-and biohelminth embryos.

The breach of these principles may cause the decrease of individual or organized collectives’ health level, initiation of the diseases of alimentary origin.

These diseases may be determined as:

- diseases caused by starvation, quality and quantity malnutrition (marasmus, protein starvation, hypovitaminosis, avitaminosis and others);

- diseases caused by the dietary intake irregularity (gastritis, stomach and duodenal ulcers, constipation or coprostasis and others);

- diseases caused by overeating (obesity, gout or podagra, hepatitis, cholecystitis, pancreatitis, gall-stone disease and etc.);

- diseases caused by inadequate culinary processing of the product (also gastritis, ulcers, hypovitaminosis etc.);

- food poisonings: bacterial origin (toxic infection, bacterial toxicosis, mycotoxicosis), non-bacterial origin (poisonous by nature products, products which became toxic after storage conditions disturbance and others); products contaminated by toxic substances (pesticides, heavy metals salts and etc.);

- enteric bacterial, virus, zoogenous infections (typhoid fever, paratyphoid A, B, dysentery; hepatitis A, poliomyelitis, enterovirus diseases; brucellosis, foot-and-mouth diseases, tuberculosis and others); geo- and biohelminthes (ascarid, whipworm, beef, pork tapeworm, trichina, fish tapeworm, flukes and etc.);

- effects, caused by the products, contaminated with mass destruction weapon in modern war – nuclear explosion radioactive products, battle poisonous substances (chemical agents), especially particularly dangerous bacterial agents.

That is why the regular medical control of the nutrition validity and safety of both individuals and organized collectives is necessary.

The following methods of such control may be used:

- the nutritional status research and assessment of people under control;

- the abovementioned alimentary diseases detection;

- the energy consumption and nutrient requirements determination or calculation;

- the factual nutrition assessment by questioning, budget, gravimetric, laboratory methods, food establishment sanitary inspection methods, and calculative methods of the daily intake energetic and nutritional content assessment.

Organism nutritional status and method of its assessment

The nutritional status is the physiological state of the organism depending on nutrition. The nutritional status is determined by: the body weight correlated with age, sex, human constitution, metabolism biochemical indices, presence of the alimentary and alimentary caused disorders and disease symptoms.

The study of the nutritional status of the individual or organized collective with similar physical load, emotional stress and general nutrition allows the objective nutrition assessment and timely detection of the alimentary caused health disorders and diseases (energy-protein, vitamin, macro-, microelement deficiency and etc.). The nutritional status assessment together with the energy consumption and 24/7 intake validity is one of the first and basic control methods of different sex and age, social and professional groups of people.

The following categories are determined in the nutritional status classification:

1. Optimal: the physiological state and body weight correspond to the height, age, sex, physical activity gravity, intensity and load.

2.                Excessive: may be due to the hereditary tendency, overeating and deficient physical activity. It’s accompanied with body weight increase, obesity. The obesity has four levels (I – adipopexis 15-20% greater than normal body weight; II – 30-49%; III – 50-99%; IV – 100% and more);

3.                Insufficient: when body weight is behind the age and height. It may be caused by the undernutrition (quantitative and qualitative), by hard and intensive physical work, emotional and psychological stress etc. Except the categories above, professor P.E. Kalmycov (St. Petersburg, Russia) suggests to add the following:

4.                Pre-disease (premorbid), caused (in addition to the abovementioned) by the different organism physiological disorders or the most evident intake defects (energy, protein, fat, vitamin, macro and microelement deficiency);

5.                Morbid (unhealthy) – weight loss caused by the disease, starvation (strong intake defects both quantitative and qualitative). The starvation may take two forms – alimentary cachexia (severe weight loss, marasmus), edematous which may be caused mostly by the protein lack at the intake. The vitamin deficiency - in avitaminosis (scorbutus, beriberi, rachitis and others), other nutrient deficiencies show themselves in corresponding pathology forms.

The complex indices: subjective (questionnaire, interrogation) and objective are used for nutritional status assessment of the individual or collective with similar labor conditions and nutrition.

The questionnaire and interrogation data have to include the following information:

-      passport data, sex, age, occupation;

-      harmful habits (smoking, alcohol, drug usage);

-      labor conditions (labor activity types, hard physical activity, occupation hazard characteristics and intensity – physical, chemical, biological, certain organs and systems overstrain);

-      life conditions, municipal services level and quality, physical training and sport activity (type, regularity), the family or organized collective economical capabilities;

-                     characteristic of nutrition in last 1-3 days: food intake quality, hours and places of food intake, meals, products and their weight list, culinary handling quality and others.

The most important and informative among the objective indices are the following:

1. Somatoscopic: medical examination of the individual body or (selectively) the collective under inspection allows to detect a lot of signs which characterize their nutrition by quality and quantity.

The constitutional type (normosthenic, hyposthenic), figure harmonicity, skeleton and ribs deformation, platypodia (flat-foot), leg curvature (signs of suffered before rachitis), fatness (normal, thinness, obesity), skin, mucous membranes and nails paleness, cyanosis, nail deformation and frailness as signs of protein, vitamin, microelement deficiency in nutrition may be detected during general medical body examination. The xerosis, keratomalacia, blepharitis, conjunctivitis, photophobia as A and other vitamin hypovitaminosis signs may be detected during the physical examination of mucous membranes of the eyes.

2. Somatometric: measuring of the body height, weight; chest, shoulder, waist, pelvis, hip girths and subcutaneous fat thickness (under inferior angle of the scapula, on the middle backside of the shoulder, lateral surface of the thorax, abdomen).

The weight-height indices may be calculated based on this measuring:

2.1. Brock index – normal body weight (BW) in kg is body height (BH) in cm minus 100 (105 or 110):

for males:    with height 155-165 cm                      BW = BH – 100

with height 166-175 cm                      BW = BH – 105

with height above 175 cm                  BW = BH – 110

The body weight for females has to be 5% less than for males in all cases.

2.2. The normal body weight may be determined according to the special nomograms (fig.), V.I. Vorobiov’s nomogram (fig.).

The point “H” on the left scale corresponds to the height (cm), the point “B” on the right scale corresponds to the thorax girth (cm). The body weight P₁ (in kg) can be found on the middle scale “P” after drawing the direct line through both these points.

The horizontal line is drawn from the point of the height on the scale “H” to the scale P and “ideal” body weight P₂ may be determined. The normal body weight P_n may be calculated as an arithmetic average. P_n =

2.3. The ideal (normal, recommended) body weight for 25-30 year old males and females may be determined according to the table 1.

2.4. The Quetelet weight-and-height index (biomass index (BMI)) may be calculated according to the following formula: BMI =

where: BW – body weight, kg; HT – height, m.

The nutrition status assessment by BMI according to the WHO recommendations is represented in the table 2.

2.5. Maximum allowable body weight according to the sex, age and height is represented in the table.

Nomogram for the normal body weight determination.

 

Nomogram for the normal body weight determination (by V.I. Vorobyov)

Ideal body weight according to the age

 

 

Assessment of the nutritional status according to the biomass index (ВМІ)

 

 

Maximum allowable body weight according to sex, age and height

 

 

2.6. The constitutional type may be determined by finding out the angle created by costal margins and the top of the xiphoid process of sternum. The result is: 90 – normosthenic type; sharp (< 90) – asthenic type; obtuse (> 90) – hypersthenic type.

 

2.7. Figure harmonicity is determined according to the following formula:

where: FH - figure harmonicity, %

  A - chest girth in pause, cm

  HT - height, cm

Results assessment:        FH between 50 and 55%- harmonic;

FH < 50% - disharmonic, poor development;

FH > 55% - disharmonic, excessive development.

 

2.8. Comparative quantity of the body weight adipose component is the sum of the four subcutaneous fat thickness which were named above, point 2 (selectively) (see table 4).

 

Subcutaneous fat thickness as a degree index of the obesity

 

 

3. Physiometric indices of the nutritional status. The energy and plastic nutrition adequacy may be assessed using the muscular strength (hand, torso dynamometry, ergometry), the pulse and breath rate registration after physical activity and both by using the fatigue indices such as tremometry, chronoreflectometry, number search etc. which are studied in “Occupational hygiene” part.

Such functional tests as capillary resistance, adaptometry and other may be used for organism vitamin sufficiency assessment. They are studied at the next lesson.

4. Clinical indices are the symptoms of the alimentary origin diseases (gastritis, stomach and duodenal ulcers, liver and gallbladder diseases, podagra, gout, hypo-, avitaminosis etc.).

5. Biochemical indices include hematological, urological and other indices of the nutritional status (see table 5).

6. The nutritional status of the individual or collective with similar labor conditions and nutrition may be researched and assessed comparing of the organism energy consumption due to hard physical activity and the calculated nutrient requirements based on these data, the calculations or laboratory researches of the qualitative and quantitative components will be studied at the next lesson in details.

The list of biochemical and hematological tests used for the nutritional status assessment (obligatory)

 

 

 

Fig. 23.2 Thickness measuring caliper

 

Classification of Vitamins.

http://www.chemistry.wustl.edu/~courses/genchem/Tutorials/Vitamins/home.htm

The vitamins may be classified as under:

 I. Fat Soluble; II.Water Soluble

I. Fat Soluble Vitamins.

These are: (1) Vitamin A or Fat Soluble A (Retinol) is a glamour or protective vitamia Akin to a fertiliser of "lawn" it performs a variety of functions in the epithelial tissues in the body. It is a safety valve for the visual process and the lung tissues.

It is anti-infective and growth-promoting vitamin. Its deficiency causes the following effects:

1.       Retards growth and lowers resistance to bacterial infection.

2.       Xerosis. Xerophthalmia, or dryness and infection.

3.       Night blindness (inability to see in dim light) due to retardation of the regeneration of visual purple.

4.       Atrophy of the cells of salivary glands and mucous membrane of the intestines,

5.       Dryness of skin owing to atrophy of the sweat and sebaceous glands or Keratinisation of epithelial tissues; a condition resembling "Toad skin" occurs,

6.       Formation of phosphatic calculi,

7.       Respiratory infections like common colds, bronchitis etc.

8.       Faulty development of teeth and spongy gums.

Pro-vitamin A is present in abundance in the yellow pigment of plants known as Carotene which has been isolated in the pure form. Fat soluble Vitamin A is present in milk, butter, ghee, fish fat, cod liver oil, kidneys, mutton, eggs and other animal fats. Green leafy vegetables, fruits, carrots, cabbage, mangoes and papaya are rich sources of vitamin A. It is not destroyed by ordinary cooking, although if cooking is prolonged or if the food is exposed to air it gets destroyed. Human requirement for vitamin A is 5,000 International Units for adults daily, being equivalent to 1.2 microgramme of carotene.

(2) The Sun Shine Vitamin D (Anti-Rachatic Vitamin) fotoRickets.jpg  transforms calcium and phosphorus into bones. It is essential for good teeth, better sleep, relaxation and for prevention and cure of rickets and osteomalacia. It is thermostable i.e., withstands high temperature uninjured. It is present in egg yolk, cod liver oil, halibut liveroil, butter fat and ghee, etc., in the form of Cholecakiferol (Vitamin D3). Cod liver oil is the richest source of vitamin D. In this respect 5 eggs are equivalent to 1 teaspoonful of cod liver oil.   Calciferol   is   a   preparation produced by the irradiation of ergosterol with ultraviolet rays and is termed as vitamin D2. Naturally it is produced in the skin by the action of ultraviolet rays of sun. A liberal supply of vitamin D to mothers during gestation and lactation renders their children less susceptible to rickets. Moreover, it corrects, improper balance of calcium and phosphorus intake and is necessary for their absorption. Its deficiency leads to rickets and dental caries in children and osteomalacia in adults, particularly among women observing purdah or persons dwelling in dark houses, where sunshine is not readily accessible. Daily requirement of this vitamin in children and adults is 400-1000 International Units.

(3) Vitamin E or Anti-Sterility Vitamin. It was discovered by Dr. Evans of U.S.A. who named it Vitamin E. It is also a fat soluble vitamin. It is stable to heat and light, but is destroyed on oxidation, specially in the presence of alkaline salts. It promotes reproduction. It is present in wheat, cereal embryos, green leaves of plants and some vegetable oils. Tocopherol, an oil extracted from wheat germ is the most potent known source of Vitamin E. Its deficien­cy leads to death of foetus in uterus and sterility in males and females of the lower animals. It is therapeutically used in threatened and habitual abortion.

(4) Vitamin K or Coagulation Vitamin. It is essen­tial for the normal coagulation of the blood. Its sour­ces are green leaves, spinach, cauliflower, cabbage, carrot-tops, etc. The part of the plants which con­tains chlorophyll usually has the largest amount of vitamin K. It is stable to heat. Its main function is the formation of prothrombin. Its deficiency leads to hypoprothrombinemia, occurrence of haemor­rhages in the skin and subcutaneous tissues of organs due to prolongation of blood-clotting.

II. Water Soluble Vitamins.

These are: (1) Vitamin B Complex. If а members of this group are absent from the diet, they produce:

Cardiovascular symptoms such as loss of breath on exertion, palpitation and precordial pain.

Anorexia leading to complex distaste for all food and relieved by aneurin.

Diminution of nerve excitability leading to peripheral neuritis hypoaesthesia and pain along the nerve trunks.

From the complex mixture the following con­stituents have been isolated:

(i) Vitamin B₁  is sensitive to heat Aneurine hydrochloride or Thiamine is the synthetic preparation used. It is considered anti-neurotic and anti beri-beri, dry or wet. It's deficiency is like "an automobile with a full tank of gasoline, but no spark to ignite it". As a morale vitamin, a lack of it means loss of appetite, indigestion, constipation, nausea, weak heart muscles, palpitation, breathlessness and degeneration of nervous system. It is present in brewers yeast, beans, bran, wheat germ oil, sun flowers seeds, nuts particularly ground nut, meat, fish, eggs etc. Milk and highly milled rice are its poor sources. The use of anti-biotics and alcohol adversely affects this vitamin. The daily requirement of this vitamin is 2 mg.

(ii) Vitamin B₂. It is of great value in human nutri­tion. It is designated as Riboflavine. It is a water soluble yellow pigment and is found in yeast, milk, eggs, fishroe, pork, liver and green leafy vegetables. It is highly heat stable and survives even canning. It is essential for the main­tenance of normal fat metabolism. Ocular manifes­tations, chelosis, photophobia, burning, itching an­gular stomatitis, glossitis and dermatitis of skin are due to its deficiency, which occurs most commonly in those individuals or communities whose diet con­sists mainly of milled rice. The estimated daily re­quirement of this vitamin is about 2-3 m. gms.

(iii) Vitamin P.P (Pellagra-preventing factor) Niacin or Nicotinic Acid is the factor concerned in pellagra. It is remarkably stable, capable of withstanding heat, oxidation and ultra violet light. It maintains healthy condition of skin and mucous membrane. Its sources are meat, liver, kidneys, yeast, whole meal flour, bread, green vegetables, mangoes, etc. Its deficiency leads to pellagra which is charac­terised by 3 D's—dermatitis, diarrhoea and demen­tia. The most typical symptom is erythema. Its daily requirement is about 15-30 m. gms.

(iv) Vitamin B₆, or Pyridoxine or anti-Dermatitis Vitamin. It is essential for normal protein metabolism. It is necessary for haemoglobin syn­thesis and also as an anti-dermatitis factor. It is present in rice polishing, yeast, liver, yolk of eggs, fat, peanuts and wheat germs. Its deficiency leads to muscular dystrophy, rigidity and dermatitis in rats.

(v) Biotin, Vitamin H. It is related to fat and car­bohydrate metabolism. Its chief sources are liver, eggs, yeast and cereals. Its deficiency causes der­matitis and eczema. Its daily requirement is 150 m. gm.

(vi) Folk Acid. It stimulates blood formation. It is important for haemopoietic factor and is used extensively in macrocytic and pernicious anaemia. It is present in liver, kidneys, yeast and leafy vegetables.

(vii) Inositol (Mouse Anti-Alopecia Factor). It is associated in some way with metabolism or transport of fat. It is important for anti-alopecia factor. Its deficiency is characterised by loss of hair.

(viii) Vitamin B₁₂ Cyanocobalamin. It has been isolated from liver. It cures pernicious anaemia in very small doses. It is a "Pep" vitamin for a healthy nervous system and the production and development of red blood cells. It is highly useful among confused, depressed, anaemic and forgetful persons. It is a costly vitamin, since about a ton of liver is required to prepare only 20-25 m.gm. of vitamin B12.

(ix) Para-Amino-Benzoic Acid. It helps tissue oxidation.

(x) Pantothenic Acid. It is also known as "chick anti-dermatitis factor." It is used in the form of cal­cium salt, which is a white crystalline salt and is odourless. Its deficiency causes burning on the soles and palms, dermatitis and defective vision. Its daily human requirement is 100 m. gm.

(xi) Choline. Its deficiency causes deposition of fat in liver, degeneration of liver and kidneys. Its daily requirement is 2 gms.

II. Vitamin C or Anti-Scorbutic Vitamin. It is chiefly present in all living tissues, fresh fruits such as oranges, lemons, tomatoes, turnips, potatoes and fresh green vegetables. This vitamin is destroyed on prolonged heating and in preservation of fruits. It is an anti-scorbutic vitamin. It is essential for maintaining capillary in­tegrity and for formation of intercelluar substance. It is essential for the maturation of red blood cor­puscles. Its deficiency leads to scurvy, a disease characterised by swelling of gums, anaemia, bad teeth, offensive breath, spongy gums, loss of weight, delayed healing of wounds and haemorrhages. The average daily requirement of this vitamin is 50-100 m. gms. Since vitamin C cannot be stored in the body so a daily intake of the recommended dose is neces­sary for good health. 

Vitamin P. It occurs naturally along with vitamin C in fresh fruits, particularly  lemons and fresh salads. It helps in preventing capillary permeability and its deficiency leads to purpura, spontaneous capillary haemorrhages and infiltration of lungs resembling tuberculosis.

Nutritional Diseases:

Important nutritional diseases are listed as hereunder:

1. Protein Calorie Malnutrition (PCM).

(i) Kwashiorkor. It results from consumption of very low protein in diets of low biological values, yet providing just enough energy to satisfy the needs of the child. This condition is usually seen in children between the age group of 1-4 years. This symptom is characterised by pitting oedema, anaemia, retarded growth, loss of appetite, diarrhoea, scanty hair growth...

(ii) Marasmus. It is a clinical condition of protein energy malnutrition, primarily due to totardeprivation of the requisite calories required by the body. It usually occurs in the age group of 1/2 to 5 years. This syndrome is characterised by failure to gain weight, wasting of muscles and of subcutaneous fat. The child feels good appetite but is irritable.

(ii) Marasmic-Kwashiorkor. Patients suffering from Marasmic-Kwashiorkor show clinical symptoms of both Marasmus and Kwashiorkor.

2. Protein Deficiency in Adults. Protein deficiency in adults is also quite prevalent in poverty areas. Protein  deficiency  will  result  in  adults  having reduced weight, reduced subcutaneous fat, anaemia, greater susceptibility to infection, frequent loose motions, general lethargy, delay in healing of wounds and oedema.

3. Mineral Deficiencies

(i) Deficiency of iodine in water and feed leads to goitre,

(ii) Lack of flourine ( < 0.5 ppm) in water leads to caries

(iii) Calcium deficient diets lead to rickets and osteomalacia

(iv) Iron deficiency diets lead to anaemia,

(v) There are other important minerals like copper, selenium etc.Usually their requirements are so little that deficiency conditions do not occur.

4.      Vitamins Deficiencies,

(i) Lack of vitamin A results in xerophthalmia, Bitot's spots, night blindness and keratomalacia.

(ii) B Complex: Deficiency of Thiamine leads to beri beri. Niacin deficiency results in pellagra.

 

Riboflavin deficiency symptoms are angular stomatitis, cheilosis, scrotal dermatitis and   corneal  vascularisation. 

 Other   B   Complex eficiencies also result in glossitis, cheilosis and angular stomatitis,

(iii) Vitamin C deficiency leads to scurvy, spongy bleeding gums, haemorrhages in skin and other haemorrhages,

(iv) Vitamin D deficiency result in rickets and osteomalacia.

 (v) Vitamin K deficiency leads to hypoprothrombinaemia, which further leads to haemorrhages.

5.      Problems  of Over-nutrition. 

(i) Obesity: The main features of obesity are overweight and fatness.It is mostly caused by overeating and intake of abun­dance of calories

 

 (ii) Hypervitaminosis A is at times caused by excess of vitamin A therapy. The manifes­tation are headache, nausea, vomiting, irritability and anorexia. Carotenaemia is also caused due to excessive consumption of carrots which is charac­terised by yellow skin with normal conjunctiva,

 (iii) The toxic manifestations of hypervitaminosis D are anorexia, nausea, vomiting, thirst, polyuria and drowsiness. Calcium and phosphorus levels in serum and urine are raised. Calcium may be deposited in many tissues also,

 (iv) Fluorosis occurs if fluorine is available > 1,5 mg in water. It is characterised by (a) dental fluorosis, i.e., mottled enamel of teeth and (v) skeletal fluorosis i.e., dense bone formation, severe spondylitis and even calcifications of ligaments of spine and tendinous inflamation of other muscles in severe cases.

Effects on health

Obesity, especially central obesity (male-type or waist-predominant obesity), is an important risk factor for the "metabolic syndrome" ("syndrome X"), the clustering of a number of diseases and risk factors that heavily predispose for cardiovascular disease. These are diabetes mellitus type 2, high blood pressure, high blood cholesterol, and triglyceride levels (combined hyperlipidemia). An inflammatory state is present, which — together with the above — has been implicated in the high prevalence of atherosclerosis (fatty lumps in the arterial wall), and a prothrombotic state may further worsen cardiovascular risk.

Apart from the metabolic syndrome, obesity is also correlated (in population studies) with a variety of other complications. For many of these complaints, it has not been clearly established to what extent they are caused directly by obesity itself, or have some other cause (such as limited exercise) that causes obesity as well. Most confidence in a direct cause is given to the mechanical complications in the following list:

• Cardiovascular: congestive heart failure, enlarged heart and its associated arrhythmias and dizziness, cor pulmonale, varicose veins, and pulmonary embolism

• Endocrine: polycystic ovarian syndrome (PCOS), menstrual disorders, and infertility

• Gastrointestinal: gastroesophageal reflux disease (GERD), fatty liver disease, cholelithiasis (gallstones), hernia, and colorectal cancer

• Renal and genitourinary: urinary incontinence, glomerulopathy, hypogonadism (male), breast cancer (female), uterine cancer (female), stillbirth

• Integument (skin and appendages): stretch marks, acanthosis nigricans, lymphedema, cellulitis, carbuncles, intertrigo

• Musculoskeletal: hyperuricemia (which predisposes to gout), immobility, osteoarthritis, low back pain

• Neurologic: stroke, meralgia paresthetica, headache, carpal tunnel syndrome, dementia^[4]

• Respiratory: dyspnea, obstructive sleep apnea, hypoventilation syndrome, Pickwickian syndrome, asthma

• Psychological: Depression, low self esteem, body dysmorphic disorder, social stigmatization

While being severely obese has many health ramifications, those who are somewhat overweight face little increased mortality or morbidity. Some studies suggest that the somewhat "overweight" tend to live longer than those at their "ideal" weight. This may in part be attributable to lower mortality rates in diseases where death is either caused or contributed to by significant weight loss due to the greater risk of being underweight experienced by those in the ideal category. Another factor which may confound mortality data is smoking, since obese individuals are less likely to smoke^{[citation needed]}. Osteoporosis is known to occur less in slightly overweight people.

Metrics

In the clinical setting, obesity is typically evaluated by measuring BMI (body mass index), waist circumference, and evaluating the presence of risk factors and comorbidities.^[1] In epidemiological studies, BMI alone is used to define obesity.

BMI

BMI, or Body Mass Index, was developed by the Belgian statistician and anthropometrist Adolphe Quetelet.^[5] It is calculated by dividing the subject's weight in kilograms by the square of his/her height in metres (BMI = kg / m²) or (BMI = weight(lbs.) * 703 / height(inches)²).

The current definitions commonly in use establish the following values, agreed in 1997 and published in 2000:^[6]

• A BMI less than 18.5 is underweight

• A BMI of 18.5 - 24.9 is normal weight

• A BMI of 25.0 - 29.9 is overweight

• A BMI of 30.0 - 39.9 is obese

• A BMI of 40.0 or higher is severely (or morbidly) obese

• A BMI of 35.0 or higher in the presence of at least one other significant comorbidity is also classified by some bodies as morbid obesity.^[7][8]

BMI is a simple and widely used method for estimating body fat.^[9] In epidemiology BMI alone is used as an indicator of prevalence and incidence.

BMI as an indicator of a clinical condition is used in conjunction with other clinical assessments, such as waist circumference. In a clinical setting, physicians take into account race, ethnicity, lean mass (muscularity), age, sex, and other factors which can affect the interpretation of BMI. BMI overestimates body fat in persons who are very muscular, and it can underestimate body fat in persons who have lost body mass (e.g. many elderly).^[1] Mild obesity as defined by BMI alone is not a cardiac risk factor, and hence BMI cannot be used as a sole clinical and epidemiological predictor of cardiovascular health.^[10]

Waist circumference

BMI does not take into account differing ratios of adipose to lean tissue; nor does it distinguish between differing forms of adiposity, some of which may correlate more closely with cardiovascular risk. Increasing understanding of the biology of different forms of adipose tissue has shown that visceral fat or central obesity (male-type or apple-type obesity) has a much stronger correlation, particularly with cardiovascular disease, than the BMI alone.^[11]

The absolute waist circumference (>102 cm in men and >88 cm in women) or waist-hip ratio (>0.9 for men and >0.85 for women)^[11] are both used as measures of central obesity.

Body fat measurement

An alternative way to determine obesity is to assess percent body fat. Doctors and scientists generally agree that men with more than 25% body fat and women with more than 30% body fat are obese. However, it is difficult to measure body fat precisely. The most accepted method has been to weigh a person underwater, but underwater weighing is a procedure limited to laboratories with special equipment. Two simpler methods for measuring body fat are the skinfold test, in which a pinch of skin is precisely measured to determine the thickness of the subcutaneous fat layer; or bioelectrical impedance analysis, usually only carried out at specialist clinics.^{[citation needed]}

Other measurements of body fat include computed tomography (CT/CAT scan), magnetic resonance imaging (MRI/NMR), and dual energy X-ray absorptiometry (DXA).^[12]

http://healthylife123.blogsome.com/

ANALYSIS AND EVALUATION OF THE NUTRITION STATUS OF THE ORGANISM.

Nutritional Status

Nutrition is the science of food, the materials or nutrients in food, what they do and how they interact — all in relation to health. Proper nutrition is an important factor in health, and malnu­trition is an important factor in the etiology of several of the major causes of death and disability in our contemporary society. Atherosclerotic vascular disease, hypertension, obe­sity, tooth decay, osteoporosis, diabetes, and cancer are com­mon diseases in which nutrition is closely involved.

Nutrition - is the main biological need of the human. Wrong nutrition influences on development of an organism, lowers its protective forces, can cause many illnesses.  Our bodies require constant supply of energy and raw materials to maintain vital functions and to rebuild cellular structures and tissues worn out in the day-to-day processes of living. In addition to calories, we need specific nutrients in our diet, such as proteins, vitamins, and minerals. It is possible to have excess food and still suffer from malnourishment, a nutritional imbalance caused by a lack of specific dietary components or an inability to absorb or utilize essential nutrients.

 Studying and rational correction of nutrition of the population is very actual problem as the adequate balanced diet forms a basis of preventive maintenance of initial alimentary diseases and of alimentary caused somatic diseases.

The nutritional status is physiological conditional of organism, which cause by nutrition. It characterizes by many indexes and symptoms, which cause by nutrition. Doctor must be able quickly estimate the breach of nutrition status of organism with the help of external signs and simple methods of investigations and give recommendations about additional investigation which is necessary do. Investigation of nutritional status consists of some indexes: status of protein, carbohydrates, fat, vitamins and mineral, clinical symptoms of alimentary diseases and anthropological indexes of physical development.

The nutritional status of an individual depends on the adequate supply of essential nutrients required by the tissues for their proper functions. This ratio between supplies and requirements of nutrients determines the nutritional status. It is good if supplies of nutrients are sufficiently adequate. An unfavourable ratio between nutrients supply and requirement results in poor nutritional status, which is usually due to:

1. Poor and inadequate diet — most common cause.

2. Interference with ingestion, absorption and utilization by tis­sues of nutrients.

3. Increased excretion and destruction of nutrients as in certain diseases.

4. Increased requirement but poor supply of nutrients e.g. in grow­ing children, pregnancy and lactating period, physical activity and metabolic disorders. That is why children, expectant and lactating women are vulnerable to malnutrition.

5. Poor eating and food habits, which are intensely personal and are difficult to change.

6. Increased stress and strain in life.

7. Poverty: With low income the person cannot afford adequate diet.

8. General illiteracy and ignorance about the importance of food nutrients to health.

Determination of Nutritsonai Status

In order to determine the nutritional status of a community or any group thereof, the following points should be determined and as­sessed properly.

1. Name, age, sex, occupation, address etc. of the persons.

2. General clinical examination: Under this general physique, muscular, skeletal and fat development of the body is noted. The condition of the skin face, lips, teeth, tongue, eyes and thyroid etc is also recorded. Thickness of the skin folds especially of triceps and subcapsular regions are also useful indications.

3. Laboratory investigations: Under this blood Mb and routine examination of stool and urine are carried out. Various biochemical tests, although quite useful, are cumbersome and time consuming and are, therefore, not done on mass scale.

4. Diet survey: For its correct assessment, one must be well versed with the composition of different types of food articles and their caloric values. The ultimate stress has to be on the type and amount of nutrients rather than on names of food articles consumed.

5. Anthrometric measurements: These are records of height, weight, chest in expiration and full inspiration and abdomen measurement. Standard weights have been tabulated according to sex, age, height, chest and abdomen measurements. This, is, in general, an easy method of assessing the nutritional status of a person.

6. Various measurements and indices with regard to determina­tion of nutritional status are as follows:

·  Thickness of skin fold e.g. those of triceps and subcapsular regions measured with skin calipers.

·  Arm circumference: Arm circumference at midpoint does not vary much in children of 1-5 years of age group irrespective of their sex. However it does vary from 10 cm to 16 cm depending to the state of nutrition of the child. Usually midpoind of left upper arm is measured and compared with the standard record.

·  Head and chest circumference: To assess the nutritional status of children under one year, the measurement of cirumference of head and chest is useful. If chest measurement is less than the circumference of head, it indicates malnutrition.

·  ACH index or Arm, chest and hip index. ACH index measurment is quite simple and practicable, provided the standard for various races are predetermined.

·  Body mass index (BMI) or formula Ketle. Other standards based on weight and height measurements have been developed for specific uses. These include the BMI (index Ketle), already discussed, and the ponderal index.  The ponderal index is the ratio of height (in meters) to the cube root of the weight (in kilograms).

7. Record the signs and symptoms of nutritional diseases, espe­cially with regard to total calories intake, protein, vitamins, calcium and iron deficiencies.

To sum up, in mass survey of nutritional status, general health of the persons with various measurements and presence of gross nutri­tional diseases are recorded and their results assessed accordingly to determine the nutritional status.

http://healthysteps.health.ivillage.com/weightobesity/bodycomposition2.cfm

 

Evaluating body fatness

Skin fold measurements are made with skin fold calipers. The following procedures must be used for each skin fold site:

1.     Use your thumb and index finger of both hands to "draw up" a layer of skin and fat.

2.     "Draw up" the skinfolds in a vertical line. Do not pinch the skinfold.

3.     Once you have drawn the skinfold, let go with your right hand and pick up the caliper.

4.     Place the jaws of the caliper over the location of the skinfold, allow the tips of the caliper to close n the skinfold at a level about where the skin would naturally be.

5.     Let the caliper adjust for two or three seconds, not the thickness of the skinfold in millimeters.

6.     Three measurements should be taken at each site. Use the average to determine your measurement.

Skinfold location for women

• Triceps - One half the distance between the soulder and elbow, use your dominant side.

• Iliac Crest - Diagonally on the natural line of the skin on the iliac crest.

• Abdominal - One inch to the right of the navel

 

Skinfold loactions for men

• Thigh - See above

• Chest - Above and to the right of the right nipple. May be done diagonally.

• Abdominal - One inch to the right of the navel

 

Calculating fatness from the skinfold

• Sum the three skinfolds

• Use the skinfold sum and your age to determine your percent fat in the body composition chart

http://www.winhealth.co.uk/Weight.htm

 

Bioelectric Impedance

Most people don't realize that there is only one "direct" method of measuring body composition that is close to 100% accurate, and that is an autopsy - performed Post Mortem. All other current methods for measuring body composition rely on "indirect" measurements techniques and are called In Vivo methods - meaning they are performed on a living body.

In Vivo methods give estimates of percentage of body fat, fat-free mass, muscle, bone density, hydration, or other body components. Each method uses one or more measurable body component (such as skinfold thickness, resistance, etc.) to make educated predictions about the other components. These predictions are based on years of research that define statistical relationships between different body components.

According to the National Institutes of Health, no trial data exist to indicate that one method of measuring body fat is better than any other for following overweight and obese patients during treatment. Good results depend upon accurately taken measurements and an adequate, scientifically derived database. Every measurement method has strengths as well as defined sources of error. Most research studies employ several methods used in combination.

Body composition equipment manufacturers should have scientific studies available to support accuracy claims, but often companies fail to explain the problems encountered in day-to-day use outside of the controlled environment of a research lab. Tanita feels it is very important for people to fully understand the benefits - and limitations - of body composition analysis. This information will enable people to make better decisions about which method is the best or most appropriate for their particular needs.

Body Composition Models

There are two basic body-composition models: the two compartment model - fat-free mass and fat; and the four compartment model - bone/mineral, protein, water and fat.

The more traditional methods are based on a two-compartment model that simply divides the body in to fat and fat-free mass. Hydrodensitometry (underwater weighing) is based on the two compartment model.

Newer, more sophisticated techniques, such as DEXA (dual energy x-ray absorptiometery) measure the body as multiple compartments. This approach improves the accuracy of the calculation for determining the real density of fat-free mass.

Reference Models

Often referred to as "gold standards," these are clinical techniques that have been validated through repeated scientific studies and against which other clinical and field method results are evaluated. The two main reference models today are Hydrodensitometry and DEXA.

Prediction Equations

In Vivo methods use equations to predict percentage of body fat, fat-free mass, muscle, hydration, etc. Using a form of statistics known as multiple regression analysis, this allows an unmeasurable component, such as body fat, to be predicted from one or more measured variable, where studies have proved there is a correlation. For example, calipers use external skinfold measurements (a method that estimates fat found just under the skin) to calculate total body fat. BIA measures the body's impedance (resistance) to an electrical signal to estimate total body fat.

Equations can be population specific (developed for specific types of people, including such categories as gender, age, ethnicity, fitness level, disease, etc.) or generalized to cover a wide range of people types. A given equation is validated according to how well the results match the results of the reference method.

It is important to note that the results of reference methods themselves do not agree 100 percent. Therefore, when comparing different methods or products, you should consider which reference method was used and the appropriateness of both the method and particular product for the body type being analyzed.

 

 

Description / Procedure: There are many devices available that measure body composition through bioelectrical impedance. This method relies on the assumption that fat is a relatively poor conductor of electricity, while lean tissue and water are good conductors. An electric current is passed through the body and, with equations, lean and fat percentages can be calculated. In practice the machines used to measure percent body fat (%BF) this way are either scales, hand-held devices, or electrodes placed on the feet and hands.

For example, with one of the more complex devices the subject lies on their back on a non conducting surface, with legs apart and arms away from the body. A pair of electrodes are placed on the hand and wrist, and another pair placed on the ankle and foot (usually opposite sides of the body).

The simplest devices are just slightly more complex than a bathroom scale.

Equipment Required: Bioelectric Impedance Analyser.

Advantages: very simple and quick to perform

Disadvantages: The equipment is relatively expensive (units on the low end of the scale are available for about $75), with prices ranging up to thousands of dollars. The impedance measure is affected by body hydration status, body temperature, time of day, and therefore requires well controlled conditions to get accurate and reliable measurements. However, the low end models can be effectively used to monitor gains or loss of body fat when used consistently over time.

Other Comments: Bioelectric impedance analysis is based on the principle that the resistance to an applied electric current is inversely related to the amount of fat-free mass within the body.

This method is possibly the favorite method of gyms as devices are cheap and easy to use. They are also 'fun' and clients like to be measured by an electronic gadget. Accuracy and precision may be poor in bioelectrical impedance used in such circumstances. There are too many assumptions and factors which can skew results; if hydration status is slightly off from normal (basal) level the reading will be incorrect. In practice this method would be accurate and precise if the subject is measured first thing after waking, in good health, has not eaten or drank anything for 12 hours and has consumed no caffeine or alcohol for 24 hours. While these facts favor the use of a bathroom-scale-type home model, they make use in the gym setting less desirable. Many times gym staff measure subjects often after a hard sweaty workout.

Body Mass Index

Body Mass Index or BMI is calculated by taking a person's weight in kilograms and dividing it by his/her height in meters squared. For instance, if your height is 1.82 meters, the divisor of the calculation will be (1.82 * 1.82) = 3.3124. If your weight is 70.5 kilograms, then your BMI is 21.3 (70.5 / 3.3124). Calculate your BMI now.

To calculate your BMI using weight in pounds and height in inches, either convert the English measurements to metric units or use the following formula.

weight (pounds) x  705  height (inches)  height (inches)

Correct Use of BMI:  BMI uses a weight to height ratio to estimate critical fat values at which the risk of disease increases. In truth, BMI does not calculate a percent body fat value, but a number indexed against disease risk. However, the most common uses do not index BMI against risk. You will find both methods in the scoring section below. 

The higher the figure the more overweight you are. Like any of these types of measures it is only an indication and other issues such as body type and shape have a bearing as well. Remember, BMI is just a guide - it does not apply to elderly populations, pregnant women or very muscular athletes.

Description / Procedure: BMI is calculated from (M) and (H).

BMI = M / (H x H), where M = body mass in kilograms and H = height in meters.

The higher the score usually indicating higher levels of body fat.

Scoring:

Equipment Required: scales and a yard stick or tape measure for determining weight and height.

Target Population: BMI is often used to determine the level of health risk associated with obesity.

Advantages: simple calculation from standard measurements

Disadvantages: BMI can be inaccurate, for example with large and muscular though lean athletes scoring high BMI levels which incorrectly rates them as obese.

Other Comments: There are a number of flaws with the BMI measurement. To start with, BMI only indicates the degree of being over- or underweight, and does not reveal what the underlying problems are. It also makes no account for the distribution of obesity; indeed, where fat is distributed on the body has been linked to increased risk of certain diseases. BMI is more reliable for assessing disease risk (such as cardiovascular diseases and some cancers) when used in conjunction with waist-hip ratio (WHR). Other measures of body composition would be preferable if available.

 

Hydrostatic Weighing

Note: Commonly called "under water weighing" by laymen

Description / Procedure: The dry weight of the subject is first determined. The subject, in minimal clothing, then sits on a special seat, expels all air from the lungs and is lowered into the tank until all body parts are emerged. Underwater weight is then determined.

Scoring: Body density = Wa/(((Wa-Ww)/Dw)-(RV + 100cc)), where Wa=body weight in air (kg), Ww=body weight in water (kg), Dw=density of water, RV=residual lung volume, and 100cc is the correction for air trapped in the gastrointestinal tract.

Equipment Required: Hydrostatic weighing tank, including scale, weighted belt, nose clip.

Advantages: Underwater weighing is the most widely used test of body density and is the criterion measure for other indirect measures.

Disadvantages: The equipment required to do underwater weighing is expensive. The tanks are mostly located at university or other research institutions, and there is generally not easy access for the general population.

Other Comments: Residual lung volume is required for the calculations. For more accuracy it should be measured, though there are calculation for RV estimation. One estimation of residual volume is one third of forced vital capacity (FVC).

 

Dual-Energy X-Ray Absorptiometry (DEXA)

Description / Procedure: The DEXA instruments differentiate body weight into the components of lean soft tissue, fat soft tissue and bone, based on the differential attenuation by tissues of two levels of x-rays.

Equipment Required: DEXA machine.

Advantages: DEXA measurements are based on a three compartmental model rather than two compartment as in most other methods. It can also distinguish regional as well as whole body parameters of body composition.

Disadvantages: The equipment is expensive, and often requires trained radiology personnel to operate.

Other Comments: If not for the limiting price of measurement, DEXA would be considered the criterion method of body composition analysis.

 

Skinfold Measurement

Description / Procedure: Estimation of body fat by skinfold thickness measurement. Measurement can use from 3 to 9 different standard anatomical sites around the body. The right side is usually only measured. The tester pinches the skin at the appropriate site to raise a double layer of skin and the underlying adipose tissue, but not the muscle. The calipers are then applied 1 cm below and at right angles to the pinch, and a reading taken 2 seconds later. The mean of two measurements should be taken. If the two measurements differ greatly, a third should then be done.

The Sites: the following descriptions are for the site at which the skinfold pinch is taken. The caliper is then applied 1 cm below and at right angles to the pinch. I have added some lay terms (in brackets) that may help the non-medical users  to find the correct sites for taking the skinfold measurements.

Triceps	A vertical pinch at the mid-point between acromial (boney tip of shoulder) and olecranon processes (pointy bit of elbow) on the posterior (back) surface of the arm.
Biceps	The pinch position is at the same level as for triceps, though on the anterior (front) surface of arm.
Subscapula	The pinch is made 1 cm below the lower angle of the scapula (bottom point of shoulder blade), the fold lifted directed down and laterally (away from the body) at about 45 degrees.
Axilla	The pinch is made at the intersection of a horizontal line level with the bottom edge of the sternum (breast bone), and a vertical line from the mid axilla (middle of armpit). (usually males only)
Iliac Crest	The pinch is made at a site immediately above the iliac crest (top of hip bone), at the mid-axillary line. The fold is directed anteriorly and downward.
Supraspinale	The pinch that is directed anteriorly and downward is made 7 cm above the spinale (front part of iliac crest), on a line from the spinale to the axilla.
Abdominal	The vertical pinch is made 4 cm adjacent to the umbilicus (belly-button)
Thigh	A vertical pinch is made at the mid-point of the anterior surface of the thigh, midway between patella (knee cap) and inguinal fold (crease at top of thigh).
Calf	A vertical pinch is made at the point of largest circumference on medial (inside) surface of the calf.
Chest	A diagonal pinch is made between the axilla and nipple as high as possible on the anterior axillary fold (males only).

 

Results: Because of the increased errors involved, it is not appropriate to convert skinfold measures to percentage body fat (%BF). It is best to use the sum of several sites to monitor and compare body fat measures. In order to satisfy many of you who want a %BF measure, I have included a couple of equations for calculating this. There are hundreds of equations available, and it is best to use one that is based on a sample that most closely resembles you. You will find that you get different results depending on the equations you use.

Some of the following equations give a measure of body density (D), which then needs to be converted to %BF using the Siri equation: %BF = 495/D-450.

Body Fat Percentage

Fat percentage Calculators:- Your personal body fat percentage is simply the percentage of fat your body contains. If you are 150 pounds and 10% fat, your body consists of 15 pounds fat and 135 pounds lean body mass (bone, muscle, organ tissue, blood etc. Fat is an essential component of your body make up and you should take note of the minimum fat percentages for healthy living!

Please use our body fat percentage calculators. There are three of them. The first two are in lbs and inches and the third one is in Kgs and Centimeters. Please don't mix them up as the readings will obviously be wrong. The results are indicative only and represent the closest approximation based on the data provided by you. They are also based on broad test sample and take no account of frame size and bone structure. Below the two calculators is a range of theoretical results to either see which band you are in or which band you would like to be in.

Anthropometric, health and demographic indicators in assessing nutritional status and food consumption

Approximately 790 million people in the developing world subsist on diets that are deficient in energy. About 200 million children suffer from malnutrition and 2 billion people suffer from a variety of micronutrient deficiencies. The vast majority of the food-insecure, whether their malnutrition is due to deficiencies in energy or in micronutrients, live in low-income developing countries and mainly in the poorest areas of those. These numbers are only estimates, since no direct data are actually available to assess the magnitude of these problems, identify the causal factors thereof, or describe the nutritional status of the poor.

At the World Food Summit (WFS) in 1996, governments and heads of state committed themselves to reducing the number of undernourished people to half its current level (then estimated at 840 million) by the year 2015. In order to monitor progress towards this goal, the WFS called for better information to identify the food-insecure and vulnerable groups, assess the extent of low food intake and undernutrition, and ascertain the main causes contributing to food insecurity and vulnerability to malnutrition. Better information is expected to facilitate the identification of appropriate policy and programme responses and the targeting of interventions to improve food security and nutrition.

With this objective, governments undertook to define, develop and periodically update a Food Insecurity and Vulnerability Information and Mapping System (FIVIMS), regrouping data on food-insecure and vulnerable people - what socio-economic categories they belong to, where they are located, and what degree of food deficiency and undernutrition prevails among them. National data will be integrated into international databases collaborating in this exercise. The latter will be linked through a common, decentralized system for posting and disseminating information, allowing to better monitor food security and nutrition trends at the global level.

At the national level, the WFS called for close attention to monitoring the availability and nutritional adequacy of food supplies, particularly in areas at high risk of chronic or seasonal food insecurity and among nutritionally vulnerable groups. It also called for mechanisms to be established for collecting information on the nutritional status of the poor and on members of vulnerable and disadvantaged groups at sub-national levels. This note presents relevant methods in this context and their population dimensions.

Possible causes of low food consumption and poor nutritional status

Low or inadequate food consumption - and consequent poor nutritional status - may be the result of a variety of causes, often operating in combination. Figure 1 illustrates the array of relevant factors. It shows that key determinants of food consumption are food availability (whether from local production or other sources) and people’s access to that food (i.e. their capacity to produce or purchase). In addition, aspects related to the stability of supplies over time (obtaining a steady flow of food from an inherently irregular production) are essential. The stability of access to food (e.g. stable income) is important in terms of food security.

The above determinants are in turn affected by the socio-economic and political environment at large, in particular by economic conditions at the macro and micro levels (importance and characteristics of the agricultural sector; trade relations; livelihood systems; etc.). Educational levels and cultural values also play a role in shaping food habits, consumption patterns and food supply systems in general.

At the individual level, the degree of efficiency with which the body utilizes the food consumed is a key determinant of nutritional status. That efficiency is generally affected by poor health conditions and reduced significantly by specific diseases (infections, intestinal parasites, diarrhoea etc.).

 

Assessing nutritional status in a population

A variety of methods are commonly used for assessing the nutritional status of populations based on anthropometric, clinical and biochemical measurements. Although methods based on dietary characteristics do not directly measure nutritional status, they are very often used by nutritionists in the field to assess it. These methods are described below and the main indicators recommended in the context of FIVIMS are presented in Table 1.

 

 

Figure 1. Determinants of food consumption and nutritional status: a conceptual framework

Anthropometric measurements (body dimensions and composition) are often used as proxies for assessing the eventual extent and severity of malnutrition. The classical indicators in this respect have to do with the growth of children and body composition of adults. The most commonly used measurements are the body weight, height, age and sex of each individual, which allow to calculate the following indicators:

Weight-for-age (W/A) reflects body mass relative to chronological age

Low W/A is influenced by both the height of the child (height-for-age) and his or her weight (weight-for-height). Its composite nature makes interpretation complex. For example, weight-for-age fails to distinguish between short children of adequate body weight and tall, thin children. However, in the absence of significant wasting (see next paragraph) in a community, similar information is provided by weight-for-age and height-for-age as both reflect the long-term health and nutritional experience of the individual or population. In general terms, the world-wide variations and age distribution of low W/A are similar to those of low height-for-age.

Weight-for-height (W/H) reflects body mass relative to height

Low W/H (wasting or thinness) indicates in most cases a recent and severe process of weight loss, which is often associated with acute starvation and/or severe disease. However, wasting may also be the result of a chronic unfavourable condition. Provided there is no severe food shortage, the prevalence of wasting is usually below 5 percent, even in poor countries. The Indian subcontinent, where higher prevalence rates are found, is an important exception. A prevalence exceeding 5 percent is alarming given a parallel increase in mortality that soon becomes apparent. On the severity index, prevalence rates between 10-14 percent are regarded as serious, and above or equal 15 percent as critical. Typically, the prevalence of low weight-for-height shows a peak in the second year of life. Lack of evidence of wasting in a population does not imply the absence of current nutritional problems: stunting and other deficits may be present.

Overweight is the preferred term for describing high W/H. Even though there is a strong correlation between high W/H and obesity as measured by adiposity, greater lean body mass can also contribute to high weight-for-height. On a population-wide basis, high W/H can be considered as an adequate indicator of obesity, because the majority of individuals with high W/H are obese. Strictly speaking, the term obesity should be used only in the context of adiposity measurements, for example skinfold thickness.

 

Height-for-age (H/A) reflects height relative to chronological age

Low H/A is called stunting. Stunted growth reflects failure to reach linear growth potential as a result of sub-optimal health and/or nutritional conditions. On a population-wide basis, high levels of stunting are associated with poor socio-economic conditions and increased risk of frequent and early exposure to adverse conditions such as illness and/or inappropriate feeding practices. Similarly, a decrease in the national stunting rate is usually indicative of improvements in overall socio-economic conditions of a country.

The world-wide variation of the prevalence of low H/A is considerable, ranging from 5 percent to 65 percent among the less developed countries. In many such settings, prevalence starts to rise at the age of about three months; the process of stunting slows down at around three years of age, after which mean heights run parallel to the reference curve. Therefore, the age of the child modifies the interpretation of the findings: for children below 2-3 years, low H/A probably reflects a continuing process of "failing to grow" or "stunting"; for older children, it reflects a state of "having failed to grow" or "being stunted". It is important to distinguish between the two related terms, length and stature: length refers to the measurement in recumbent position, the recommended way to measure children below 2 years of age or less than 85 cm tall; whereas stature refers to standing height measurement. For simplification, the term height is used to cover both measurements.

Body Mass Index

(BMI)= weight (in kg) ¸ [height (in m) squared] reflects also body mass relative to height and is mainly used for adults and adolescents. High BMI permits to assess degrees of overweight and obese people and low BMI to assess different levels of thinness (and of chronic energy deficiency).

At the level of an entire population, the information gathered through the above indices provides a basis for assessing the prevalence of unsatisfactory conditions under one or the other of the relevant criteria. In practice, the indicators will then be:

a.      For children under age five, the Z-score classification system is used for population-wide assessments including surveys and nutrition surveillance. For consistency with clinical screening, prevalence-based data are commonly reported using cut-off values, usually at minus two and plus two Z-scores from the median in the reference population ^[3]. This implies that slightly more than 2 percent of the reference population will be classified as "malnourished" even if they are truly "healthy" individuals with no growth impairment ^[4].

o    Prevalence of underweight children is the percentage of children with a weight that is more than two Z-scores below the referenced weight-for-age.

o    Prevalence of stunted children is the percentage of children with a height that is more than two Z-scores below the referenced height-for-age.

o    Prevalence of wasted children is the percentage of children with a weight that is more than two Z-scores below the referenced weight-for-height.

For adults (active, usually 20-49 years), although reference data are less validated than for children, recommendations for threshold to be used are:

o    for thinness:

grade 1: BMI 17.0 - 18.49 (mild thinness)

grade 2: BMI 16.0 - 16.99 (moderate thinness)

grade:  3: BMI <16.0 (severe thinness)

o    for overweight

o      grade 1: BMI 25.0 - 29.9 (mild overweight)

o     grade 2: BMI 30.0 - 39.99 (moderate overweight)

o     grade 3: BMI ³ 40 (severe overweight)

As a first step in the implementation of the FIVIMS, these indicators are presented in concise and analytical reports called Nutrition Country Profiles (NCP), prepared by FAO in collaboration with the countries. Mapping is used in the National Country Profiles to illustrate the main nutritional problems affecting the population. Selected maps from the NCP of India, illustrating the main indicators used to assess the nutritional situation in a country:

·         Map 1 (PDF, 2.7KB)deals with the prevalence of underweight among children under five years of age. A prevalence rate above 30 percent is considered as very high; in effect, except Nagaland (29.5 percent, high), Mizoran (23.4 percent, high) and Meghalaya (13.0 percent, medium) all the states are in a severe situation.

·         Map 2 (PDF, 2.7KB)deals with the prevalence of stunting among children under five years of age. Prevalence above 40 percent is considered as very high; here again, all states except Goa (low prevalence), Manipur and Meghalaya (medium) and Mizoram (high) have a very high prevalence of stunting.

·         Map 3(PDF, 2.7KB) deals with the prevalence of wasting among children under five years of age. This indicator, very often used to assess acute malnutrition, is very sensitive and may change very quickly. When its value is greater than or equal to 15 percent, the situation of children is critical; between five and nine percent it is poor; and between 10-14 percent it is serious. Meghalaya and Himachal Pradesh show a much better situation than other states. However, for all states in orange the situation for this indicator is less critical than for the two preceding ones.

·         Map 4 (PDF, 2.9KB) deals with the prevalence of a Body Mass Index inferior to 18.5 and with differences between men and women on this score. The results are in total agreement with children's indicators and enable some explanation for the origin of malnutrition between food intake and health conditions.

·         Map 5 (PDF, 3.1KB) deals with the prevalence of vitamin A deficiency among children under six years of age and show that generally the situation is worse in the northern part of India with some exception.

The same indices listed above for children under five can also be calculated for children between ages five and ten. This is less commonly done although it also represents very useful information. Finally, measurements are also taken for adolescents (ages 11-17) and for adults above 50 years, but such measurements are difficult to use because the reference values are less well established for these age groups.

Anthropometry-based nutritional assessment has the advantage of being a universally applicable, inexpensive and non-invasive method. This procedure also is applicable to large sample sizes. It can be used to identify target groups of population or areas for intervention, as a tool for nutritional surveillance, and in cross-sectional evaluation.

However, the nutritional status of children alone is not in itself a good indicator of the nutritional status and of food inadequacy (an important explanatory factor of nutritional status) of a population, for two reasons. At the macro level, children under age 10 account for 22 percent of the total population in the developing regions as a whole and 11 percent in the developed ones. Their energy requirements, even in areas with a young age structure, represent at most 15 percent of the requirements of the total population. At the micro level, intra-household food allocation is not necessarily balanced (because of socio-cultural factors that influence the patterns of distribution), so the children’s nutritional status does not necessarily reflect that of the household as a whole.

Clinical signs of some disorders associated with micronutrient deficiencies are also used to describe and quantify the nature and extent of malnutrition; the most usual ones are listed in Table 1. Vitamin A deficiency is detected and measured through assessing the prevalence of night blindness; iodine deficiency, through assessing the prevalence of goitre; and iron deficiency, through assessing anaemia by measuring haemoglobin concentration.

The sources of the data used in NCPs are selected on the basis of their quality. Demographic surveys - in particular the Demographic and Health Surveys (DHS), which cover numerous developing countries - are one of the main sources of anthropometric data on mothers and children. These surveys have allowed preparing maps showing the prevalence of malnutrition ion the world at national and sub-national level. These surveys should be encouraged and the measurements of other age and sex groups (children above five, adolescents and the elderly) should be carried out in order to enrich the knowledge of the causal factors of malnutrition when necessary.

Measurement of food supply and consumption

The purpose of nutritional epidemiology is to evaluate the impact of food consumption (macronutrients and micronutrients) on the health status of the population. All the existing approaches to evaluating food consumption are based on the same principle, i.e. the comparison of energy and nutrient intakes with the estimated requirements of the population. Those approaches are presented below.

1 The food inadequacy approach

The food inadequacy approach developed by FAO attempts to assess the number of people and proportion of the population with inadequate food consumption by comparing a country’s Dietary Energy Supply (DES) obtained from the FAO Food Balance Sheets (FBS) to the energy requirements of individuals.

Since the DES is an average, estimating the proportion of the population that is underfed ^[6] requires some notion of the inequality in distribution of that supply within the population. This method also necessitates a good estimate of the minimum per person dietary energy requirements in the population considered. This in turn requires information on body stature and on levels of physical activity in the population considered.

Although this method might provide a good proxy of food consumption at national level, its validity is limited by the inaccuracies of food balance sheets and by the difficulties in obtaining a correct estimation of energy requirements of populations. Moreover, this method only provides national averages and does not provide any information on intra- and inter-household inequalities in food consumption.

2 Food consumption measures

The methods most commonly used to assess food intake are described briefly below. They can be classified in two major groups. Those of the first group provide a measure of food consumption and include the weighing method, the food record method, the 24-hour recall method and the food frequency method. Those of the second group provide an estimate of food consumption using income/expenditure/budget surveys.

2.1 Food consumption measures

Weighing method

This method is usually applied at the household level but can also be used for individuals. Food items to be used are weighed before the preparation of each meal, while information on the food consumed outside the home is obtain by interviewing each member of the household. This method is very accurate but cannot be used for long periods because it is time-consuming and expensive. Therefore, it cannot measure food consumption over time.

Food record method

In this method an individual regularly records the type and quantity of all food consumed. This method is accurate but requires very careful training and supervision by the survey taker and the close co-operation and motivation of the respondents for the task to be carried out consistently.

24-hour recall method

In this method, the respondent is asked to recall his/her food intake during the last 24-hour period. The interviewer records a detailed description of all foods and beverages consumed. This is most appropriate for assessing average intakes of foods and nutrients for large groups of individuals. This method is suitable at individual level but cannot be carried out for long periods of time because it is too demanding for the respondent.

Food frequency questionnaire

In this method, the interviewer records the frequency of the consumption of some specific food items associated with the phenomenon that needs to be described. This is the choice method in nutritional epidemiology, mainly in the field of non-communicable diseases.

2.2 Estimates of food consumption: income/expenditure/budget surveys

This method enables estimating food consumption from an assessment of the household food expenditures. As with the FAO food inadequacy approach, this method, which may be precise at household level, does not inform on the intra-household distribution of food.

Food balance sheets (national level)

·          Dietary energy supply per person (total and major food groups) as a proxy of food intake

·          Proportion of energy provided by animal products.

·          Proportion of energy provided by proteins (and quantities supplied).

·          Proportion of energy provided by lipids (and quantities supplied).

·          Proportion of animal proteins in total protein.

·          Proportion of animal fats in total lipids.

 

Food consumption indices (national, sub-national, urban, rural)

·       Per person total energy intake

·       Contribution of the major food groups to energy intake, when available

·       Average intake of essential nutrients (protein, vitamin A, iron, iodine etc.)

 

 It shows the average energy intake (kilocalories per consumption unit per day) and the respective contributions of protein, fat and carbohydrates in energy intake. A consumption unit (CU) corresponds to the energy requirements of a referenced man aged 20-39 years weighing 60 Kg, doing sedentary work. The energy coefficients of all the other individuals in the household are calculated proportionately based on energy requirements according to age, sex, physiological status and activity pattern. Based on the nutrient requirements and recommended dietary allowance for India (1990) the energy requirement of the CU is 2,425 Kcal.

Health and demographic indicators

Certain demographic and health indicators are very useful to better understand some aspects of malnutrition, either at the national level or for smaller geographic entities as required by the specific policy question at hand. The indicators most commonly used in this context relate to the following:

• Population size and density. These characteristics have an indirect influence on general aspects and characteristics of the food supply system - its size, spatial extension, complexity - and the magnitude of possible food problems to be tackled.

• Age and sex distribution. This is needed to assess the size of critical groups (children under five, the elderly, women of childbearing age etc.). Also, age and sex structures heavily affect the dependency ratio.

• Fertility. It determines the numbers of pregnant and lactating women, a nutritionally critical category. It also has an influence on household size, which in turn is correlated with some nutritional indicators.

• Urban-rural population distribution. Energy expenditure varies significantly between rural and urban residents. And, of course, their respective food supply systems differ markedly.

• Proportion of agricultural population in total population. This is a measure of a population’s dependence on its own agricultural resources (vs. foreign trade) for subsistence.

• Life expectancy - the main indicator of general health conditions at the population level.

• Infant and child (0-4 years) mortality rates. These are more specific indicators of health conditions for a sensitive sub-population. They often give leads regarding nutritional conditions, especially around weaning.

• Morbidity rates for important diseases - diarrhoea, measles, acute respiratory infection, AIDS.

Socioeconomic indicators

Socio-economic indicators are useful to gain some understanding of societal conditions that are known to affect people’s access to food. Those most commonly used to document the said conditions are::

• Gross domestic product (GDP) per person. ()This is the best single indicator of average living standards in a population, but - leaving aside inherent difficulties of estimation and error margins - its main limitation is that a given average level of per person income may give rise to quite different nutritional outcomes depending on the degree of inequality in income distribution.

• Proportion of people below the poverty line. This indicator addresses the above drawback and attempts to assess the size of the population which, because of its economic conditions, has limited and irregular access to food. (The poverty line, i.e. the minimum income required to cover basic needs, obviously depends much on the cost of securing basic food requirements.)

• Human Development Index (HDI). This composite index combines data on GDP, education and health so as to also encompass some non-economic dimensions of well-being and "development". The HDI adds valuable dimensions in international comparisons; when the matter is assessing country situations, however, it is best to resort to specific data from the social sectors deemed relevant. Information on educational levels, for instance, often is useful, especially as it relates to women, who usually are in charge of many nutrition- and health-related functions in the household.