Food, Nutrition and Health: Nutrients, Balanced Diet and Deficiency Disease
Nutrients and energy
Macronutrients - carbohydrates, proteins and fats - supply energy: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g. Micronutrients - vitamins and minerals - supply no energy but regulate body processes. A balanced diet supplies all nutrients, fibre and water in the proportion needed for age, sex and activity. ICMR-NIN groups foods into five groups: cereals and millets; pulses, eggs, meat and fish; milk and milk products; vegetables and fruits; fats, oils and sugar.
Deficiency diseases
- Protein-energy: kwashiorkor (protein deficiency with oedema, moon face, fatty liver) and marasmus (severe energy and protein deficiency with wasting, no oedema).
- Vitamin A - xerophthalmia and night blindness. Vitamin B1 - beriberi. Vitamin B3 - pellagra (dermatitis, diarrhoea, dementia). Vitamin C - scurvy. Vitamin D - rickets in children, osteomalacia in adults. Iodine - goitre. Iron - anaemia.
Worked example
A plate contains 60 g carbohydrate, 20 g protein and 15 g fat. Energy = (60×4) + (20×4) + (15×9) = 240 + 80 + 135 = 455 kcal. Reasoning: multiply each gram figure by its own factor, keep the three products separate, and never use 9 for protein.
Traps
- Reversing kwashiorkor and marasmus - oedema belongs to kwashiorkor.
- Using 4 kcal/g for fat or 9 kcal/g for carbohydrate.
- Treating vitamins as energy sources.
- Omitting fibre and water when describing a balanced diet; the exam expects them named.