Nutrition is a science of food and its relationship to health. Nutrition refers to nourishment that sustains life. The study of nutrient requirements and the diet providing these requirements is also known as ‘nutrition’.  It includes the uptake of food, liberation of energy, elimination of wastes and all the processes of synthesis essential for maintenance, growth and reproduction.. It is a relatively new science with roots in physiology and biochemistry and is interrelated to various other subjects like Medicine, Agriculture, Food science & technology, Biochemistry, Biological sciences, Economics, Psychology, etc.

‘Balanced diet’ is defined as that ‘diet providing adequate nutritional needs as well as extra allowance for stress from different foods belonging to different food groups in specific quantities and proportions’. Since all foods don’t have similar nutritional quality, the nutrients provided and thus the health depends on the choice & quantity of foods selected. For a healthy & active life, diets should be planned on sound nutritional principals. Optimum nutrition /adequate nutrition or good nutrition is a diet “that provides all dietary nutrients in respect of kind and amount, and in proper state of combination or balance, so that the organism may always meet the varied exogenous and endogenous stresses in life, whether in health or disease, with a minimal demand or strain on the body’s natural homeostatic mechanisms”. Thus while planning the diet, in addition to the calorific value, the quantity and quality of food(Vitamins & Minerals) is taken into consideration. The three proximate principles of food are Protein, Carbohydrate and Fat. The main energy food sources are carbohydrate and fats; whereas for growth and development protein food sources are required. Deficiency, excess or imbalance of nutrients results in malnutrition, which could be either under nutrition or overnutrition. Proper nutrition is required for prevention of illness as well as for treatment of the illness.


 Vitamins are organic compounds. Although they are required in small amounts, but are essential for many important functions of the body. They can not be synthesized by the body. Due to shortage of specific vitamins various deficiency diseases could occur. The vitamins were designated by letters A, B and so on before their structures were determined. Foods contain small quantities of these vitamins.


Minerals are required for many purposes like forming the frame and rigid structure of the body, as part of the body/cell fluids and for number of cellular and sub cellular physiological functions.