requires a balance of the right nutrients, that is, getting the proper amount, or proportion, of each one.
Our diet should provide adequate amount of all nutrients to maintain good health and physical efficiency. Daily food intake should be such that of the total consumption, about 15 to 20% is protein, 40 to 50% is complex Carbohydrates and 20 to 30% is fat.
Carbohydrates
Carbohydrates are organic compounds which may be simple and complex. It include sugars and starches. All carbohydrates are eventually broken down into glucose which is absorbed and utilized by the body in various ways. Glucose is required by red blood cells and is the main source of energy for the brain. It is also essential for the oxidation of fat and for the synthesis of certain non-essential amino acids. Simple carbohydrates like sugar and sugar enriched food is broken down easily and soon absorbed into the blood stream whereas complex carbohydrates like starches take longer time to be broken down by digestive enzymes hence providing a slower and more gradual supply of glucose.Carbohydrates are the primary source of energy which provide about two-thirds of an individuals total energy needs. Sugars are found in glucose (its basic form) and sweets, biscuits, chocolates, pastries, honey, fruits etc. Starches are found in a wide range of foods including cereals, grains, pulses, bread, beans, potatoes, other vegetables
and fruits which are far more useful as they contain accompanying fibre, vitamins and minerals. It is sensible to eat more starch rich foods as excess sugar rich foods may lead to obesity, high blood sugar, tooth decay and a possible increased risk of developing diabetes in later adult life.
The percentage of calories derived from carbohydrates should be at least 40% in well balanced diets. But this consumption differs country wise depending on the difference in diets. While in developing nations it is as high as 60-70%, it is 40-50% in Europe and 30-40% in USA.
Proteins
Proteins are the structural components of the body forming the basis of cells, tissues and organs. They are a large group of organic compounds consisting of carbon, hydrogen, nitrogen and oxygen atoms. Some contain sulphur and phosphorus also. When the proteins are digested they break down into smaller units called amino acids. Of the 20 basic amino acids 12 can be manufactured by the body and the rest, called the 'essential amino acids' must be obtained from food.Proteins help to repair worn out or diseased tissues and to build new ones. It is used in the formulation of hormone, enzymes, red blood cells and antibodies. It also provides amino acids necessary for growth of fetus in pregnancy and for the production of milk proteins during lactation. Proteins are widely found in foods derived both from plant and animal sources. Plant sources include beans, peas, pulses, whole grains, nuts and oil seeds; while red meat, poultry, fish, milk, cheese, yogurt and eggs are obtained from animals. Red meat is a good source of essential amino acids and iron and is traditionally regarded as 'first class' protein. But too much consumption of red meat may be harmful as it is a major source of undesirable saturated fat. One can eat more fish or chicken without the fatty skin instead of excess red meat. Vegetarians can obtain plenty of both from plant sources, whole grain cereals and from low fat diary products. A protein deficiency especially in infants and growing children can cause growth retardation, severe wasting of muscle etc.
The dietary requirements of protein depend on age and physiological state. A part of the dietary protein is utilised or wasted to meet the energy requirements. So calorie intake should be adequate enough to meet the protein need or its maximum utilisation, taking into account the above factor.
Fats
Fats are a group of organic compounds that occur naturally in plant and animal cells in the form of lipids, consisting of carbon, hydrogen and oxygen atoms. They are an important energy store, having twice the calorific value than carbohydrates. They are broken down into its constituents parts by enzymes called lipases.Fats play a vital role in the human body and perform many functions. They are necessary for the absorption and utilization of certain vitamins like A, E, D and K. Fat deposit help to maintain body temperature against outside environmental influences and protects body organs such as the heart and the liver. Fats contain Essential Fatty Acids (EFA) which are essential for maintaining tissues in normal health.
Saturated fats such as cholesterol are found in meat and dairy products, i.e. whole milk, cheese, butter and eggs. Many processed foods have saturated fats added to them and they are widely used in manufacturing. Unsaturated fat are found in vegetable oils like soya bean, mustard, sunflower, ground nut, olive etc and corn, peanuts, seeds, olive, oily fish etc. The fat which should be eaten in excess is the unsaturated variety which is more beneficial. An excess level of saturated fats in the blood tend to raise the level of cholesterol contributing to hardening of the arteries causing strokes and various forms of heart diseases. It is advisable to limit fat intake to no more than 30% of the overall diet.
Fibre
Fibre is derived from plants and is found in fruit, green leafy and root vegetables, whole meal flour and bread, bran rich food, brown rice, cereals including oats, beans and pulses. Fibre plays a vital role in the digestive process by softening the bile wastes and speeding up the process of elimination of undigested food thus helping to prevent constipation. The presence of fibre regulates the absorption of fats and glucose into the bloodstream.Insufficient consumption of fibre may lead to the development of Colon cancer and increase levels blood cholesterol. It is recommended that at least five portions(25gms fibre) of vegetables and fruit should be eaten each day to provide necessary vitamins, minerals and fibre. Increase your fibre intake gradually and as you increase your fibre intake make sure that you increase your fluid intake as well.
Vitamins and Minerals
Vitamins are a group of organic substances that are required in minute quantities in the diet in order to maintain good health. A lack of a particular vitamin results in a deficiency disease. There are six vitamin groups such as Vitamin A, B, C, D, E , K and P.Vitamins are classified as Fat soluble vitamins and Water soluble vitamins. Fat soluble vitamins include (1)Vitamin A and Carotene ( Provitamin A), (2) Vitamin D - Vitamin D2 (Calciferol, artificial vitamin D) and Vitamin D3 ( Irradiated dehydrocholesterol), Natural Vitamin D), (3) Vitamin E and (4) Vitamin K.
Water soluble vitamins include (1) Vitamin B complex - Vitamin B1( thiamine, aneurin), Riboflavin, nicotinic acid and Nicotinamide, Vitamin B6 (Pyridoxin) , Pantotnenic acid, folic acid, Biotin, Choline, P- Amino benzoic acid, Inositol and Vitamin B12 (2) Vitamin C (3) Vitamin P
Minerals are chemical substances such as calcium, sodium, iron and potassium which act as components of main body structures like bones, teeth, blood and soft tissues. They are found in green vegetables, fruits, cereals, nuts, seeds diary products, eggs and fish. A deficiency of minerals can lead to particular conditions. For example deficiency of iron can lead to some forms of anemia.
Vitamins and minerals doesn't directly provide energy but they contribute to nutrition by allowing chemical reactions to occur normally through out the body. These reactions known as metabolism are responsible for certain functions like converting fats and carbohydrates into energy and utilizing proteins to repair injured tissues by vitamins and the production of blood and bone and transmission of nerve impulses by minerals.
Fat Soluble Vitamins
Vitamin A (retinol) is needed for the normal bone formation, maintenance of skin and tissues. The main sources of vitamin A are fish liver oils, liver of animals, diary products like butter, ghee, milk and eggs. Green leafy vegetables, red palm oil, carrot, pumpkin and ripe mango are important sources of carotene. Carotene (Provitamin A) is converted to vitamin A in the intestinal walls. A deficiency causes night blindness and possible total loss of vision, and causes the tissues to be keratinised. Adults and older children require 750mg of Vitamin A and 3000 mg of Carotene daily. But excess of Vitamin A is toxic i.e children receiving daily large doses 30,000 to 1,50,000may have headache, a dry itching sin, swelling and brittleness of bones.
Vitamin D (Calciferol) controls calcium levels in the blood, prompting increased uptake of the minerals from the digestion of food and hence making it available for bone growth and repair. The deficiency of Vitamin D causes bone deformities. The dietary sources are fish liver oils (of cod, halibut, shark), fat fish ( sardine, salmon, Herring), egg yolk and dairy products( butter, ghee, milk). D3 (Cholecalciferol) can be formed in the skin from the sun's rays. The daily requirement of Vitamin D for adults is about 200 I.U and for infants, children, pregnant and nursing women it is 400 I.U. An excess can produce toxic symptoms like loss of appetite, nausea, vomiting etc
Vitamin E comprises several compounds that are essential for the maintenance of cell membranes. It is essential for normal reproduction. The main sources are wheat germ oil, corn germ oil, vegetable oils ( Soy bean, cottonseed, sunflower, ground nut, mustard, coconut etc) cereals and eggs. Daily requirements are 25-30 mg for adults and 10-20mg for children.
Vitamin K or Phylloquinone, a Compound form, act as a coenzyme in protein synthesis in blood clotting. Inadequate intake of vitamin K by the mother may cause hemorrhagic disease of the new born. The deficiency is rare but if it occurs, the result may be severe bleeding. Green leafy vegetables ( spinach, cabbage, kale), vegetables (cauliflower, soybean, carrots, potatoes), wheat bran, wheat germ etc are good dietary sources.
Water soluble Vitamins
Vitamin B Complex includes B1 (Thiamine), B2 (Riboflavin) B3 (niacin or Nicotinic acid), B6 (Pyroxidine ), Pantotnenic acid, folic acid, Biotin, Choline, P- Amino benzoic acid, Inositol, B12 (Cyanocobalamin) etc. Vitamin B is required for the manufacture of Red blood cells, enzyme activity and for amino acid metabolism. It is essential to maintain the nerves in healthy condition, normal functioning of the skin and intestinal tract.
The main sources of B1 are dried yeast, rice polishings, wheat germ, whole cereals, liver and is found in minimal quantities in fruits, vegetables, milk etc.; Rich sources of B2, B3, B6, Pntothenic acid, Folic acid , Biotin include liver, dried east, whole and skim milk powders, peanut, rice polishings etc, good sources include meat, fish, eggs, legumes (pulses) and dhals, leafy vegetables, whole cereals etc. Vitamin B12 is present only in foods of animal origin. Liver is the richest source and meat, fish, kidney, brain and eggs are good sources. A deficiency in Vitamin B1, causes 'Beri Beri' characterized by numbness, muscle wasting and difficulty in walking; deficiency in vitamin B3 causes 'Pellagra', characterized by dermatitis (skin ailment) in the hands, feet and neck, diarrhea and dementia; while a lack of some of the others can result in Anemia and deterioration of the nervous system.
Vitamin C (ascorbic acid) is needed for maintenance of cell walls and connective tissue including blood vessels and tendons. It helps in the rapid healing of wounds and in the absorption of iron. A deficiency causes fragility of skin, blood vessels and tendons characteristics of the disease known as Scurvy. General weakness, spongy bleeding gums, loose teeth, swollen tender joints, hemorrhages in various tissues and under the skin are symptoms. Main sources of vitamin C are citrus fruits and green leafy vegetables (drumstick leaves, coriander leaves, cabbage). Gooseberry and Guava are rich sources. Orange, pineapple, lime juice, cashew fruit, ripe mango, papaya and tomato are good sources. Daily requirements are adults 50 mg and children, between 30-50 mg.
Vitamin P ( Bioflavonoids) is essential along with ascorbic acid (Vitamin C) in preventing capillary fragility. A deficiency causes decreased capillary (vessel) resistance leading to bleeding, accompanied by pain across the shoulders and in the legs. The main sources are fresh fruits (orange, apple, blackberry, cherry, plum) and vegetables (spinach, tomato, lettuce, cabbage, carrot, cauliflower, pea etc.).
Minerals
CalciumAmong minerals, Calcium is present in the highest amount in the body mostly in the skeleton. Calcium is essential for the formation of bone and teeth, for clotting of blood, contraction of heart and muscle etc. A deficiency can cause 'Osteoporosis' in which decalcification of bone occurs. Even minor accidents can cause fractures. In children, a deficiency can cause a decreased rate in growth. Small fish eaten along with bones, skim milk powder etc are excellent sources and milk, milk products like curd, sesame seeds, ragi, green leafy vegetables like carrot leaves, drumstick leaves etc are other good sources. The daily recommended allowances for calcium is Adults 400-500mg, children between 400- 700 mg.
Iron
A greater part of the Iron in the body is present as Haemoglobin. Iron deficiency causes anaemia and is widely prevalent among children, adolescent girls and expectant and nursing mothers. Cereals are the most important sources of iron for Vegetarians and the other important sources are legumes, green leafy vegetables and jaggery. Meat, fish and eggs are also important sources of iron. The daily recommended allowances for iron is Adults 20-30mg, children between15-20 mg, pregnant and nursing women need more iron.
Iodine
Iodine is a constituent of thyroxine, the active principle of the thyroid gland. The thyroid gland plays an important role in energy metabolism and in the growth of the body. A deficiency can cause enlargement of thyroid, resulting in the disease called goitre. In children, severe iodine deficiency may result in serious retardation of growth known as cretinism. Iodine requirements for adults are about 0.15 to 0.2 mg daily and for infants and children 0.05 to 0.10 mg daily. This requirement is normally supplied by a well balanced diet and by drinking water except in mountainous regions where the food and water is deficient in iodine. Crude common salt prepared from sea water and sea fish are good sources.
Sodium Chloride (Nacl)
All minerals except Sodium Chloride (Nacl) are usually present in sufficient amounts in a well - balanced diet. Sodium chloride is the only mineral which is taken in more or less pure form in addition to the amount present in natural foods. Salt taken in food is the source of Nacl. The requirements depend on the climate and occupation. People doing heavy work in hot humid climates need more Nacl. A deficiency can cause heat cramps- intense and painful contractions of skeletal muscle. But consumption of excessive amounts of Nacl causes Oedema in protein deficiency and increases blood pressure in hypertension. Foods of animal origin contain more Nacl than those of Vegetable origin. The daily requirements for tropical climates are Adults 10-15 (light work), 20-25 (hard work) and children 5-10g/day.
Potassium
The adult human body contains about 250g of potassium which is present almost entirely in the cells of different tissues, muscles, etc. Only small quantities are present in the extra cellular fluid. Potassium is the major basic of ion of the body cells. The functions of potassium are : Regulation of pH of cell contents, Regulation of the osmotic pressure of cell contents and Potassium ion increases the relaxation of heart muscle which is antagonized by calcium ion. Potassium deficiency causes weakness and muscular paralysis. But Consumption of excessive amounts of potassium also causes the similar symptoms. Deficiency seldom occurs as potassium is present in abundance of foods.
Minerals
CalciumAmong minerals, Calcium is present in the highest amount in the body mostly in the skeleton. Calcium is essential for the formation of bone and teeth, for clotting of blood, contraction of heart and muscle etc. A deficiency can cause 'Osteoporosis' in which decalcification of bone occurs. Even minor accidents can cause fractures. In children, a deficiency can cause a decreased rate in growth. Small fish eaten along with bones, skim milk powder etc are excellent sources and milk, milk products like curd, sesame seeds, ragi, green leafy vegetables like carrot leaves, drumstick leaves etc are other good sources. The daily recommended allowances for calcium is Adults 400-500mg, children between 400- 700 mg.
Iron
A greater part of the Iron in the body is present as Haemoglobin. Iron deficiency causes anaemia and is widely prevalent among children, adolescent girls and expectant and nursing mothers. Cereals are the most important sources of iron for Vegetarians and the other important sources are legumes, green leafy vegetables and jaggery. Meat, fish and eggs are also important sources of iron. The daily recommended allowances for iron is Adults 20-30mg, children between15-20 mg, pregnant and nursing women need more iron.
Iodine
Iodine is a constituent of thyroxine, the active principle of the thyroid gland. The thyroid gland plays an important role in energy metabolism and in the growth of the body. A deficiency can cause enlargement of thyroid, resulting in the disease called goitre. In children, severe iodine deficiency may result in serious retardation of growth known as cretinism. Iodine requirements for adults are about 0.15 to 0.2 mg daily and for infants and children 0.05 to 0.10 mg daily. This requirement is normally supplied by a well balanced diet and by drinking water except in mountainous regions where the food and water is deficient in iodine. Crude common salt prepared from sea water and sea fish are good sources.
Sodium Chloride (Nacl)
All minerals except Sodium Chloride (Nacl) are usually present in sufficient amounts in a well - balanced diet. Sodium chloride is the only mineral which is taken in more or less pure form in addition to the amount present in natural foods. Salt taken in food is the source of Nacl. The requirements depend on the climate and occupation. People doing heavy work in hot humid climates need more Nacl. A deficiency can cause heat cramps- intense and painful contractions of skeletal muscle. But consumption of excessive amounts of Nacl causes Oedema in protein deficiency and increases blood pressure in hypertension. Foods of animal origin contain more Nacl than those of Vegetable origin. The daily requirements for tropical climates are Adults 10-15 (light work), 20-25 (hard work) and children 5-10g/day.
Potassium
The adult human body contains about 250g of potassium which is present almost entirely in the cells of different tissues, muscles, etc. Only small quantities are present in the extra cellular fluid. Potassium is the major basic of ion of the body cells. The functions of potassium are : Regulation of pH of cell contents, Regulation of the osmotic pressure of cell contents and Potassium ion increases the relaxation of heart muscle which is antagonized by calcium ion. Potassium deficiency causes weakness and muscular paralysis. But Consumption of excessive amounts of potassium also causes the similar symptoms. Deficiency seldom occurs as potassium is present in abundance of foods.
Sources and Requirement of nutrients
| Nutrients | Requirements | Sources | |
| Children 1200-2100 kcal | Adults 1900-3900 kcal | ||
| Carbohydrate | 40-60g/100g of calories | 50-70 g/100g of calories | Glucose (its basic form) and sweets, biscuits, chocolates, pastries, honey, fruits, cereals, grains, pulses, bread, beans, potatoes, other vegetables and fruits. |
| Protein | 20-33g | 45-55g | Legumes, grains, nuts and seeds; dark leafy greens; eggs; dairy products |
| Fat | 15g | 15g | Vegetable oils like soya bean, mustard, sunflower, ground nut, olive etc and corn, peanuts, seeds, olive, oily fish etc |
Vitamins | |||
| Vitamin A | Fish liver oils, liver of animals, diary products like butter, ghee, milk and eggs, green leafy vegetables, red palm oil, carrot, pumpkin and ripe mango | ||
| Vitamin A Carotine | 300-600µg 1200-2400µg | 750µg 3000µg | |
| Vitamin D | 400 I.U | 200 I.U | Fish liver oils (of cod, halibut, shark), fat fish ( sardine, salmon, Herring), egg yolk and dairy products( butter, ghee, milk). |
| Vitamin E | 10-20mg | 20-25mg | Wheat germ oil, corn germ oil, vegetable oils ( Soy bean, cottonseed, sunflower, ground nut, mustard, coconut etc) cereals and eggs. |
| Vitamin K | Not known | Not known | Green leafy vegetables ( spinach, cabbage, kale), vegetables (cauliflower, soybean, carrots, potatoes), wheat bran, wheat germ etc |
| Vitamin B | |||
| Thiamine Riboflavin Nicotinic Acid Vitamin B6 Vitamin B12 | 03 -1.1mg 0.5-1.2mg 12-17mg 0.8-1.4mg 0.5-1.0µg | 1.2-2mg 1.3-2.2mg 19-26mg 2.0mg 1µg | Dried yeast, rice polishings, wheat germ, whole cereals, liver, fruits, vegetables, milk, peanut, meat, fish, eggs, legumes (pulses) and dhals, leafy vegetables. |
| Vitamin C | 25mg | 40mg | Citrus fruits and green leafy vegetables (drumstick leaves, coriander leaves, cabbage), Gooseberry, Guava , Pineapple, Cashew fruit, ripe mango, papaya and tomato. |
| Vitamin P | Not known | Not known | Fresh fruits (orange, apple, blackberry, cherry, plum) and vegetables (spinach, tomato, lettuce, cabbage, carrot, cauliflower, pea etc.). |
| Minerals | |||
| Calcium | 400mg | 600mg | Dairy products; dark, leafy greens, legumes; most nuts and seeds; molasses; figs, apricots; dates |
| Iron | 20-28mg | 28-30mg | Legumes (especially soybeans and soy products other than oil); dark, leafy greens; dried fruits; whole and enriched grains; molasses |
| Zinc | 10-15 mg | 15mg | Eggs, cheese, legumes, nuts, wheat germ, whole grains, some kinds of brewer's yeast |
| Sodium | 5-10g | 10-15g | Salt |
