Nutrition and Dietetics
Nutrition and Dietetics tests nutrient classification, energy calculations, deficiency diseases and the modification of diets in illness.
Core rules
- Energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g.
- A balanced diet supplies energy, all nutrients, fibre and water in correct proportion.
- Protein-energy malnutrition: marasmus shows severe wasting without oedema, weight below 60% for age; kwashiorkor shows oedema, low albumin and flaky-paint dermatosis, usually at 1–3 years after weaning.
- Deficiency mapping: vitamin A → night blindness and xerophthalmia; thiamine → beriberi; niacin → pellagra (dermatitis, diarrhoea, dementia); riboflavin → angular stomatitis; vitamin C → scurvy; iron → microcytic anaemia; iodine → goitre; vitamin D and calcium → rickets and osteomalacia.
- Therapeutic diets: diabetic (complex carbohydrate, high fibre, low refined sugar), renal (low protein, low sodium, low potassium, fluid restriction), hypertension and cardiac failure (low sodium), hepatic encephalopathy (low protein).
Worked example
A meal contains 60 g carbohydrate, 20 g protein and 10 g fat. Energy = (60 × 4) + (20 × 4) + (10 × 9) = 240 + 80 + 90 = 410 kcal. Reasoning: fat supplies 90 kcal from only 10 g, nearly a quarter of the total, which is why using 4 kcal/g for fat is the most frequent arithmetic error in this paper.
Traps that cost marks
- Swapping the marasmus and kwashiorkor pictures.
- Ignoring that boiling and prolonged cooking leach water-soluble vitamins.
- Forgetting that colostrum is rich in immunoglobulin A and must never be discarded.