Estimation of adequacy of feed.
A method of calculation of energy losses of a man and its necessities in food substances. An estimation of adequacy of feed after a menu-lay-out
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. A balanced diet must contain foods from the above three groups.
1. Conformity of entering energy to energy losses. In norm it is necessary the certain balance, or equilibrium.
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.
Methods of determination of the organism energy expenditure
Daily energy expenditure of organism consists of:
- basal metabolism which depends on the age, sex, height, body weight, physiological constitution (asthenic, normo- and hypersthenic);
- energy expenditure by gastrointestinal digestion (specific-and-dynamic effect of food) which is approximately 10% from the basal metabolism;
- energy expenditure due to physical loads and emotional stresses during the day, in other words on physical activity and rest according to the individual or collective daily routine;
- energy expenditure depends also on the local climate and weather conditions, workplace microclimate, clothes type and quality, work habits and skills (ability).
The most exact, but bulky methods of determination of the energy expenditure are the following:
- method of direct calorimetry (the heat release from the organism into special calorimetric camera);
- method of indirect calorimetry, consisting
in the gas exchange (respiratory metabolism)
(quantity of the inspired oxygen and expired carbonic
acid per hour) determination during the rest and
physical activity. The expired air is accumulated in the special
- methods of pulsometry. The special device – pulsotachometer is used for measuring the pulse rate and its filling during performance of the different types of activity and other stresses, results of which are converted in kilojoules in the device automatically;
- method of alimentary energometry is a laboratory determination of the caloric value of the daily intake including the undigested part of food;
- calculative methods: the basal metabolism is determined separately using special tables by Harris and Benedict for sex and body weight (first number) and sex, age and height (second number). The sum of these numbers is the basal metabolism. The energy expenditure for specific-dynamic effect of food which is 10% of the basal metabolism and for all types of activity which person performs during active part of the day (physical and mental work, rest, food intake etc.) is added to the basal metabolism. This energy expenditure is calculated using special tables. The energy (in calories) for different types of activity per hour is based on the daily time-keeping (monitoring). The daily monitoring is the number of hours or minutes which the person spends on each type of activity during the day.
Specialists of World Health Organization (WHO) have worked out the new method of energy expenditure determination recently (1986). Following this method, the basal metabolism (BM) and specific-dynamic effect of food are calculated using the special equations according to the age, sex, height, body weight (appendix 2). The energy expenditure is calculated as a multiplication of the BM by the physical activity coefficient (PhAC) values of which are worked out for each different type of activity (appendix 3).
Average BM values according to the sex, age, body weight and specific-dynamic effect of food (appendix 4) and physical activity coefficient (PhAC) according to the person profession (appendix 5) were worked out.
For example, the basal
metabolism of the
35-year old male -
the locksmith by profession with
BM = 11.3×70 kg + 16×1.75 m + 901 = 1 720 kcal.
At first the relative basal metabolism (RBM) per one hour is calculated for energy expenditure: RBM = BM : 24 hours. In our example the RBM is 1 720 : 24 = 71.7 kcal. Then the time keeping on each type of activity per day is determined. The corresponding PhAC for each type of activity may be found in the table of the appendix 3. The received results are written down in the table for the energy expenditure calculation:
Type of activity
The energy expenditure for each type of activity:
RBM ´ the type activity duration ´ PhAC
The daily energy expenditure is the sum of the basal metabolism with specific-dynamic effect of food and the energy expenditure by all types of activity.
The average daily energy expenditure (by sex, age, body weight see appendix 4) has to be multiplied by the corresponding profession PhAC (appendix 5) to receive daily energy expenditure value.
In our example this is: 1650×1.9 = 3 135 kcal.
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.
Balanced Diets: we must have the above items in the correct proportions.
Carbohydrates are the most important source of energy. They contain the elements Carbon, Hydrogen and Oxygen. The first part of the name "carbo-" means that they contain Carbon. The second part of the name "-hydr-" means that they contain Hydrogen. The third part of the name "-ate-" means that they contain Oxygen. In all carbohydrates the ratio of Hydrogen atoms to Oxygen atoms is 2:1 just like water.
We obtain most of our carbohydrate in the form of starch. This is found in potato, rice, spaghetti, yams, bread and cereals. Our digestive system turns all this starch into another carbohydrate called glucose. Glucose is carried around the body in the blood and is used by our tissues as a source of energy. (See my pages on respiration and balanced chemical equations.) Any glucose in our food is absorbed without the need for digestion. We also get some of our carbohydrate in the form of sucrose; this is the sugar which we put in our tea and coffee (three heaped spoonfuls for me!). Both sucrose and glucose are sugars, but sucrose molecules are too big to get into the blood, so the digestive system turns it into glucose.
When we use glucose in tissue respiration we need Oxygen. This process produces Carbon Dioxide and water and releases energy for other processes. Now try my starch test in the Virtual Laboratory
Proteins are required for growth and repair. Proteins contain Carbon, Hydrogen, Oxygen, Nitrogen and sometimes Sulphur. Proteins are very large molecules, so they cannot get directly into our blood; they must be turned into amino-acids by the digestive system. There are over 20 different amino-acids. Our bodies can turn the amino-acids back into protein. When our cells do this they have to put the amino-acids together in the correct order. There are many millions of possible combinations or sequences of amino-acids; it is our DNA which contains the information about how to make proteins. Our cells get their amino-acids from the blood. Now try my Biuret test in the Virtual Laboratory
Proteins can also be used as a source of energy. When excess amino-acids are removed from the body the Nitrogen is excreted as a chemical called urea. The liver makes urea and the kidney puts the urea into our urine.
Like carbohydrates, fats contain the elements Carbon, Hydrogen and Oxygen. Fats are used as a source of energy: they are also stored beneath the skin helping to insulate us against the cold. Do not think that by avoiding fat in your diet you will stay thin and elegant! If you eat too much carbohydrate and protein, you will convert some of it into fat, so you will put on weight. You must balance the amount of energy containing foods with the amount of energy that you use when you take exercise.
You must have some fat in your diet because it contains fat soluble vitamins.
Vitamins are only required in very small quantities. There is no chemical similarity between these chemicals; the similarity between them is entirely biological.
Vitamin A: good for your eyes.
Vitamin B: about 12 different chemicals.
Vitamin C: needed for your body to repair itself.
Vitamin D: can be made in your skin, needed for absorption of Calcium.
Vitamin E: the nice one - reproduction?
These are also needed in small quantities, but we need more of these than we need of vitamins.
Iron: required to make haemoglobin.
Calcium: required for healthy teeth, bones and muscles.
Sodium: all cells need this, especially nerve cells.
Iodine: used to make a hormone called thyroxin.
We do not can not digest cellulose. This is a carbohydrate used by plants to make their cell walls. It is also called roughage. If you do not eat foods materials which contain fibre you might end up with problems of the colon and rectum. The muscles of you digestive system mix food with the digestive juices and push food along the intestines by peristalsis; if there is no fibre in your diet these movements cannot work properly.
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);
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 (
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-
with height 166-
with height above
The body weight for females has to be 5% less than for males in all cases.
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.
Body Mass Index is calculated for an individual by taking body weight and dividing by the square of the individual's height. For any particular height, BMI is directly proportional to weight. When calculating BMI for any particular weight, BMI is inversely proportional to the square of the height. The following chart outlines the varying formulae that you can use to calculate your own BMI.
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
Total thickness of folds in mm
Fat quantity in %
20 – 30
6,7 – 12,0
9,2 – 15,0
50 – 60
18,0 – 20,2
22,0 – 24,6
90 – 100
25,0 – 26,2
30,3 – 31,8
130 – 150
29,4 – 31,1
35,4 – 37,4
180 – 200
33,2 – 34,5
40,0 – 41,5
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)
(according to the CI)
Glucose in blood
3.89 – 6.1 mmol/l
Whole protein in blood serum
60 – 78 g/l
0.494 – 0.86 mmol/l
0.59 – 1.77 mmol/l
Alkaline phosphatase activity
0.5 – 1.3 mmol/(hour×l)
Vitamin Ñ in blood
34.1 – 90.9 μmol/l
113.5 – 170.3 μmol/day
Vitamin Â2 in urine
0.82 – 2.73 μmol/day
Vitamin À in blood serum
0.52 – 2.09 mmol/l
Fine blood smear (blood formula)
Additional methods of research
Total nitrogen in daily urine
423.4 – 1213 mmol/day
Urea in daily urine
333 – 583 mmol/day
Creatinine in daily urine
0.0 – 0.314 mmol/day – for males
7.1 – 15.9 mmol/day – for females
53 – 106.1 μmol/l
Packed cell volume, PCV
40 – 48 % - for males
36 – 42 % - for females
Total cholesterol in blood serum
2.97 – 8.79 mmol/l
2.97 – 8.79 mmol/l
Pyruvic acid in blood
0.034 – 0.102 mmol/l
Lactic acid in blood
0.33 – 2.22 mmol/l
Ketone bodies in urine
Inorganic phsphorus in blood serum
0.65 – 1.29 mmol/l
Calcium in blood serum
1.03 – 1. 27 mmol/l
Iron in blood serum
11.6 – 31.3 μmol/l
1.86 – 2.79 mmol/l
Pyridoxine according to the N-methyl-nicotinamide content in urine
51.1 – 87.6 μmol/day
Fig. Thickness measuring caliper
Fig. Wood lathe auxanometer
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.
Generally, a healthy diet will include:
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;
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 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).
The Food Guide Pyramid
Good nutrition is important for everyone.
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
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:
4. Classification by nutritive value:
1) Cereals and millets
2) Pulses (legumes)
4) Nuts and oilseeds
6) Animal foods
7) Fats and oils
8) Sugar and jaggery
9) Condiments and spices
10) Miscellaneous foods
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.
Although a healthy diet is based upon nutrition, people eat foods and not nutrients; as few people know which foods supply which nutrients, allowing people to self-regulate their diets means that they run the obvious risk of deficiency. Due to past difficulties of educating people about nutrient intake, governments have opted to counsel on what foods to eat rather than on what nutrients to ingest.
Most states set guidelines for a healthy diet -- these usually vary slightly from country to country based upon demographics. These guidelines do however usually share the same recommendations of eating less fried or fatty foods to reduce cholesterol. Many guidelines suggest replacing certain foods with healthier alternatives that supply an abundance of nutrients, for instance using legumes or beans within a salad or pasta.
As BMI and weight changes from person to person, the general Reference Nutrient Intakes (RNI) set by governmental institutions may be somewhat lacking for some people, despite the fact that the RNI is generally calculated as higher than the average nutrient intake. It is even thought that some people may have needs above that of the RNI, meaning even if a person achieved nutrient intake, they would still not be fulfilling the RNI. The only real way to know the RNI for a person is to implicitly monitor the intake of nutrients and amount of exercise.
In specific individuals, ingesting foods containing natural allergens (e.g. peanuts, shellfood) or drug-induced triggers (e.g. tyramine for a person taking an MAO inhibitor) may be life-threatening.
Some foods have low nutritional value, and if consumed on a regular basis will contribute to the decline of human health. This has been demonstrated by various epidemiological studies that have determined that foods such as processed and fast foods are linked to diabetes and various heart problems.
When improperly cut or prepared, a small number of foods (such as fugu) can result in death.
The ingredient usually cited as being most crucial to good health, water, has even been known to result in death when consumed in extraordinary quantities.
From a psychological perspective, a new healthy diet may be difficult to achieve for a person with poor eating habits. This may be due to tastes acquired in early adolescence and preferences for fatty foods. It may be easier for such a person to transition to a healthy diet if treats such as chocolate are allowed; sweets may act as mood stabilizers, which could help reinforce correct nutrient intake.
It is known that the experiences we have in childhood relating to consumption of food affect our perspective on food consumption in later life. From this, we are able to determine ourselves our limits of how much we will eat, as well as foods we will not eat - which can develop into eating disorders, such as anorexia or bulimia nervosa. This is also true with how we perceive the sizes of the meals or amounts of food we consume daily; people have different interpretations of small and large meals based on upbringing.
While plants, vegetables, and fruits are known to help reduce the incidence of chronic disease, the benefits on health posed by plant-based foods, as well as the percentage of which a diet needs to be plant based in order to have health benefits is unknown. Nevertheless, plant-based food diets in society and between nutritionist circles are linked to health and longevity, as well as contributing to lowering cholesterol, weight loss, and in some cases, stress reduction.
Indeed, ideas of what counts as "healthy eating" have varied in different times and places, according to scientific advances in the field of nutrition, cultural fashions, religious proscriptions, or personal considerations.
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.
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 19th century the science of nutrition had a limited range. Protein, carbohydrate andfat had been recognized early in the 19th 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
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.
deficiency: Malnutrition is directly responsible for certain
specific nutritional deficiency diseases. The commonly reported ones in
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.
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
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.
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.
These are, for example, e.g. meat, fish, eggs milk and milk products.
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.
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.
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.
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.
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
2. Sterilizationby raising the temperature
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.
The milk is heated to 145°-
1. Holder's method: Milk is heated in
cylindrical tanks with steam passed in water jackets surrounding it to 145°-
2. Flash method or high temperature short time (H. T.S. T.) method:
Here milk is heated 1600-
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.
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.
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.
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.
A calorie is defined as the amount of heat
required to raise the temperature of
Unit of Food (
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 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.
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.
Proteins are needed by the body: -
· For growth and development: They furnish the building material, i.e. the amino acids from which the body proteins are synthesized.
· 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.
· For synthesis of antibodies, enzymes and hormones: Antibodies, enzymes and hormones contain protein. The body requires protein to produce them.
· Proteins can also furnish energy to the body, but generally the body depends for its energy on carbohydrates and fats rather than proteins.
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.
It is customary to express protein requirements
in terms of body weight. Doctors recommended
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
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.
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.
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.
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
· cakes and biscuits
· cream, soured cream and crème fraîche
· coconut oil, coconut cream or palm oil
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
· 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 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
· 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
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.
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.
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.
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.
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.
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.
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.
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:
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
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.'
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
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
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.
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.
Who needs vitamin and mineral supplements?
Many people don't receive all of the nutrients they need from their diet because they either can't or don't eat enough, or they can't or don't eat a variety of healthy foods. For some people, including those on restrictive diets, multivitamin-mineral supplements can provide vitamins and minerals that their diets often don't. Pregnant women and older adults have altered nutrient needs and may also benefit from a supplement.
Choosing and using supplements
Supplements, as the term suggests, can complement your regular diet, but they aren't food substitutes. They can't replace the hundreds of nutrients found in whole foods. But if you do decide to take a vitamin or mineral supplement, consider these factors:
Check the supplement label. Read labels carefully. Product labels can tell you what the active ingredient or ingredients are, which nutrients are included, the serving size — for example, capsule, packet or teaspoonful — and the amount of nutrients in each serving. The label also provides directions for safe use and tips for storage along with the name and address of the manufacturer, packer or distributor where you can write if you need more information on a particular product.
Avoid supplements that provide "megadoses." In general, choose a multivitamin-mineral supplement — for example, Centrum, One A Day, others — that provides about 100 Percent Daily Value (%DV) of all the vitamins and minerals instead of one that supplies, for example, 500%DV of one vitamin and only 20%DV of another. The exception to this is calcium. You may notice that calcium-containing supplements don't provide 100%DV. If they did, the tablets would be too large to swallow. Most cases of nutrient toxicity stem from high-dose supplements.
Look for “USP” on the label. This ensures that the supplement meets the standards for strength, purity, disintegration and dissolution established by the testing organization, U.S. Pharmacopeia (USP).
Beware of gimmicks. Synthetic vitamins are usually the same as so-called "natural" vitamins, but "natural" vitamins usually cost more. And don't give in to the temptation of added herbs, enzymes or amino acids — they add mostly cost.
Look for expiration dates. Supplements can lose potency over time, especially in hot and humid climates. If a supplement doesn't have an expiration date, don't buy it. If your supplements have expired, discard them.
Store all vitamin and mineral supplements safely. Store supplements in a dry, cool place. Avoid hot, humid storage locations, such as the bathroom. Also, store supplements out of sight and away from children. Put supplements in a locked cabinet or other secure location. Don't leave them on the counter or rely on child-resistant packaging. Be especially careful with any supplements containing iron. Iron overdose is a leading cause of poisoning deaths among children.
Play it safe. Before taking anything other than a standard multivitamin-mineral supplement of 100%DV or less, check with your doctor, pharmacist or a registered dietitian. High doses of some vitamins or minerals may cause health problems. For example, high doses of vitamin B-3 (niacin) can result in or worsen liver problems, and too much vitamin A over time may cause liver problems or weaken bones in women. In addition, supplements may interfere with your medications. For instance, vitamin E isn't recommended if you're taking blood-thinning medications (anticoagulants) because it can complicate the proper control of blood thinning. If you're already taking an individual vitamin or mineral supplement and haven't told your doctor, discuss it at your next checkup.
These are complex organic substances contained in food and are very essential for the normal growth and nutrition of animals. In fact, they are vital accessory food factors required for the maintenance of optimum, health. Recent observations of diseases in men and experiments on animals have shown that these diseases result from deficiency in the diet of certain constituents of fresh vegetables and animal foods called vitamins. They are present in various foods in minute quantities and diet devoid of vitamins, if taken for some period, gives rise to certain diseases known as deficiency diseases and may ultimately even cause death. They do not supply energy but are simply protective foods.
Classification of Vitamins.
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.
E or Anti-Sterility Vitamin. It was discovered by Dr. Evans of
(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 à 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.
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-
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-
(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.
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
(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.
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-
(ix) Para-Amino-Benzoic Acid. It helps tissue oxidation.
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
(xi) Choline. Its deficiency causes deposition of fat in liver, degeneration of liver and kidneys. Its daily requirement is 2 gms.
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-
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.
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) Marsmic-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:
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. Osteoporosis is known to occur less in slightly overweight people.
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. In epidemiological studies, BMI alone is used to define obesity.
BMI, or Body Mass Index, was developed by the Belgian statistician and anthropometrist Adolphe Quetelet. 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.
· 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.
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). 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.
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.
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.
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