Food and Nutrition: Nutrients, Balanced Diet and Meal Planning
This domain tests nutrient functions, sources and deficiency diseases, the five food groups, the idea of a balanced diet, and the ability to plan meals against RDA for a given person.
Nutrients at a glance
- Energy: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g.
- Protein: growth and repair. Cereals are limited in lysine, pulses in methionine - a cereal-plus-pulse meal improves protein quality.
- Fat: concentrated energy, essential fatty acids, carrier of fat-soluble vitamins.
- Deficiency signatures: vitamin A - night blindness, xerophthalmia; thiamine - beri-beri; riboflavin - angular stomatitis; niacin - pellagra (dermatitis, diarrhoea, dementia); vitamin C - scurvy; vitamin D - rickets in children, osteomalacia in adults; iron - anaemia; iodine - goitre; calcium - poor bone density.
- Water and dietary fibre are needed though they supply no energy.
Balanced diet and food groups
ICMR five food groups: cereals and millets; pulses and legumes; milk and meat; fruits and vegetables; fats and sugars. A balanced diet supplies about 60–70% energy from carbohydrate, 10–15% from protein and 20–30% from fat, with variety and fibre.
Meal planning depends on family size and composition, age, sex and activity, RDA, season and availability, budget, religion and customs, likes and dislikes, cooking time and equipment, and special states such as pregnancy or illness.
Worked example
Plan one day for a 16-year-old girl, moderate activity (about 2,300 kcal, 45–50 g protein). Breakfast: poha with vegetables and a glass of milk. Mid-morning: guava. Lunch: two rotis, dal, seasonal vegetable, curd. Evening: roasted chana. Dinner: rice, rajma, salad. Reasoning to write in the answer: cereal plus pulse covers lysine and methionine; curd and milk add calcium; guava and lemon supply vitamin C, which enhances absorption of the iron in pulses; tea with meals is avoided because tannin inhibits iron absorption.
Traps
- Confusing marasmus (wasting from energy and protein deficit) with kwashiorkor (protein deficiency with oedema).
- Claiming vitamin D comes mainly from vegetables.
- Building all meals from one food group.
- Giving RDA figures without stating age, sex and activity.