The word ‘Nutrient’ means serving as or providing nourishment, through nourishing food. If food is to remain balanced, it must have certain essential ingredients. A wholesome food means a sort of combination of such food items which contain, in a requisite and proportionate quantity, necessary vitamins, carbohydrates, proteins, minerals, fats, fruits, vegetables, food grains, animal foods etc.
Any food, which lacks in or is overloaded with a particular (essential) nutrient, is bound to invite various diseases and, when requisite quantity of each ingredient is suitably adjusted and balanced, the disease, emanating from such shortages or excesses, will either get cured or, at least, show a declining trend.
Energy and food requirements of each person vary due to one’s physical requirement, based on the mode of job one performs or has to perform. Age, gender, height, weight, work-load, (living) life style, amenability or susceptibility to particular diseases or already acquired physical disorder(s) will determine how many calories are required for an individual. Region, climate, health status, food habits existing in a particular community also are taken into consideration, while prescribing a caloric-based dietary pattern/chart. According to WHO recommendations, 3000 calories for a male and 2000 for a female are considered adequate for a moderate activity. But actual requirement will depend essentially on the determining factors, stated above.
Proteins: Non-vegetarians get energy-giving carbohydrates from eggs, meat, fish, etc. vegetarians have to depend on milk and its derivatives, pulses, soyabeans etc. For an adult 10% per day of total calorie requirements (about 65-75 gms per day), but it must not fall below 40 gms in a meal-chart.
Carbohydrates: These provide greater part of energy to a person’s diet; but no individual carbohydrate is an essential nutrient in the sense that the body needs it but cannot make it, for itself, from other nutrients (Davidson). If intake of carbohydrate falls below 100 gms per day, Ketosis may surface. Sugar is the main source of this nutrient which provides energy to body, followed by starch.
Vitamins: Vitamins ‘A’, ‘D’, ‘E’ and T are fat-soluble vitamins whereas vitamin ‘C (Ascorbic Acid), Vitamin B-complex group are ‘Water-soluble’ ones. Vitamins are organic substances in food which are required in small amounts but such vitamins cannot be sunthesised in adequate quantities. In all, there are twelve vitamins which have been demonstrated to have clinical effects in man. Vitamin-deficiency diseases are many and cannot be detailed here. Deficiency of a particular vitamin is bound to give rise to certain disorders which may appear in the form of a temporary problem of health.
Minerals etc.: In addition, Sodium, Potassium, Iron, Iodine, Chloride, Zinc, Calcium, etc. are also essential parts of daily food and their excess or decrease gives rise to many other disorders.
Fats: Due to the high caloric value fats are useful to people with a large energy expenditure. Moreover, they are helpful in cooking and making food appetising. Excess of fats causes obesity which, in turn, gives rise to killer diseases like hypertension, heart disorders. Fats are available, in plenty, from milk, clarified butter (ghee), butter, and other milk products, though most of those are rich in protein and calcium also.