Different foods have been grouped under three food groups based on their functions and major nutrient contributions :
- Energy giving foods : This group includes food rich in carbohydrates,like cereals and their products,starchy roots and tubers and sugar,and those rich in fat like nuts,fats and oils. Therefore , the energy in our diet is mainly contributed by this group. Cereals and nuts in addition to energy,contribute significant amount of protein,minerals and B-group vitamins. Fats and sugars,beside being energy dense foods add to the palatability of the diet.
- Body building foods : This group includes foods which provide proteins that are important for tissue building and maintenance. Foods of animal origin like milk and milk products,eggs,meat,fish and poultry provide proteins of good quality. As these proteins contain all the essential amino acids in right amounts and proportions needed by the body,they have a higher biological utilization. Plant protein foods like pulses legumes,nuts and oil seeds , on the other hand,have a relatively inferior quality protein. The biological utilization of these proteins is lower as they are deficient in sulphur containing energy, Vitamin A, Vitamins of B group and minerals.
- Protective foods : This group includes foods that provide ample amount of vitamins and minerals for protective and regulatory functions of the body. All vegetables (except starchy roots and tubers included under energy giving foods) and fruits comprise this group. Amongst the vegetables,most of the green leafy vegetables are good source of iron , calcium, Beta-carotene, Vitamin C and dietary fibre . Deep yellow and orange colored fruits and vegetables are particularly rich in Beta-carotene, and citrus fruits in Vitamin C