Nutrition and Dietetics
Nutrition and Dietetics - what the exam tests
This domain tests nutrients and their functions, the balanced diet and food groups, energy and protein requirements, nutritional assessment (BMI, weight-for-age), deficiency diseases, therapeutic diets and food hygiene.
Core rules
- Energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g. Vitamins and minerals are micronutrients.
- Balanced diet supplies energy, protein, fat, vitamins, minerals, fibre and water in correct proportion; Indian food groups are cereals, pulses, milk and meat, vegetables and fruits, fats and sugars.
- BMR is energy for involuntary functions; total energy = BMR + physical activity + thermic effect of food.
- Protein-energy malnutrition: kwashiorkor - oedema, moon face, low protein, often 1–3 years; marasmus - severe wasting, no oedema, usually under 1 year.
- Deficiencies: vitamin A → night blindness; vitamin D → rickets; iron → anaemia; iodine → goitre; thiamine (B1) → beri-beri; vitamin C → scurvy.
Worked example
A 50 kg adult needs about 1 g protein/kg/day = 50 g protein. A day's diet of 60 g rice (about 4 g protein), 30 g dal (7 g), 200 mL milk (6 g) and 100 g vegetables (2 g) gives only 19 g. Reasoning: the 31 g gap must be closed with pulses, egg, fish or milk; a diet that fills the stomach with rice alone can still cause protein deficiency.
Traps that cost marks
- Forgetting that fat gives 9 kcal/g, more than double carbohydrate.
- Confusing kwashiorkor (oedema) with marasmus (wasting).
- Prescribing a high-protein diet in liver or renal failure without modification.
- Missing that vitamins A, D, E and K are fat-soluble and toxic in excess.