Food and its Functions: Classification, Nutrients and Food Groups
The five food groups
- Cereals and millets - energy, some protein, B vitamins, fibre.
- Pulses and legumes (with nuts and oilseeds) - protein, B vitamins, fibre.
- Milk and milk products; meat, fish, egg - protein, calcium, fat, vitamin B12, haem iron.
- Fruits and vegetables - vitamins, minerals, fibre, antioxidants; green leafy vegetables for β-carotene, iron, folate and calcium.
- Fats and oils; sugars - concentrated energy, essential fatty acids, carriers of fat-soluble vitamins.
Functions of food
Physiological - energy-yielding, body-building, protective/regulatory. Psychological - comfort, satiety, reward. Social - festivals, hospitality, religious identity, status.
Other classifications used in answers: by origin (plant/animal), by chemical composition (carbohydrate-rich, protein-rich, fat-rich), and by function (energy-giving, body-building, protective).
Worked example
A day's menu: rice, sambar, curd rice, a banana and a teaspoon of ghee. Map it - rice = cereal group; sambar dal = pulse group; curd = milk group; banana = fruit group; ghee = fat group. The missing group is vegetables, especially green leafy vegetables, so the plan lacks carotene, folate and much of its iron and fibre. Reasoning: every item is assigned to exactly one of the five groups by its dominant nutrient contribution, and adequacy is judged by whether all five appear.
Traps that cost marks
Potato is a starchy vegetable and is often counted against cereals, not against the protective vegetable allowance. Milk forms its own group even though it supplies protein. Sugars are listed separately from fats although both are energy-dense. 'Protective foods' is not a synonym for fruits only - pulses, milk, eggs and green leafy vegetables are protective too.