Food Science and Nutrition: Nutrients, Deficiency Diseases and Meal Planning
What this domain covers
Food Science and Nutrition tests nutrient functions and sources, deficiency disorders, the balanced diet and meal planning, the effect of cooking on nutrients, food preservation, and food safety and adulteration.
Core concepts
- Energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g.
- Five food groups: cereals and millets; pulses and legumes; milk and meat products; fruits and vegetables; fats and sugars.
- Deficiency map: vitamin A → night blindness and xerophthalmia; thiamine (B1) → beriberi; niacin → pellagra with the three Ds (dermatitis, diarrhoea, dementia); vitamin C → scurvy; vitamin D and calcium → rickets in children, osteomalacia in adults; iron → microcytic anaemia; iodine → goitre; protein-energy → kwashiorkor (oedema, moon face) and marasmus (severe wasting without oedema).
- Meal planning principles: adequacy, balance, variety, economy, satiety value, seasonal and local availability, and family food habits.
- Cooking losses: water-soluble vitamins leach into cooking water; overcooking and added baking soda destroy thiamine; fine chopping increases loss. Steaming and pressure cooking conserve more than boiling and discarding the water.
Worked example
Two idlis (100 g) supply 20 g carbohydrate, 4 g protein and 0.5 g fat. Energy = (20 × 4) + (4 × 4) + (0.5 × 9) = 80 + 16 + 4.5 = 100.5 kcal. Reasoning: each macronutrient is multiplied by its own factor; applying 4 kcal to fat is the error that costs marks.
Traps
- Swapping kwashiorkor and marasmus.
- Saying fat provides 4 kcal/g.
- Assuming boiled food is always nutritious when the water is thrown away.
- Treating RDA, which carries a safety margin, as the minimum requirement.