Nutrition, Dietetics and Hydration
This domain tests the composition of a balanced diet, energy values of nutrients, deficiency diseases, therapeutic diets and fluid balance - the calculations and the practical tray decisions.
Core rules
- Energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g. One kilocalorie equals 4.184 kilojoules.
- A balanced diet supplies cereals, pulses, milk or meat, vegetables and fruits, a little fat, and 8–10 glasses of safe water daily.
- Protein-energy malnutrition: marasmus - severe wasting, weight for age below 60%, no oedema; kwashiorkor - oedema, low albumin, moon face, hair and skin changes.
- Deficiency diseases: vitamin A - night blindness and xerophthalmia; thiamine - beriberi; niacin - pellagra (dermatitis, diarrhoea, dementia); vitamin C - scurvy; vitamin D - rickets; iron - anaemia; iodine - goitre.
- Therapeutic diets: diabetic (complex carbohydrates, no refined sugar), low-sodium (under 2 g salt daily in hypertension and cardiac failure), renal (restricted protein, sodium and potassium), high-protein and high-calorie for burns and tuberculosis. Progressive diets: clear liquid → full liquid → soft → normal.
- Hydration: about 1500–2000 mL per adult per day unless restricted; record intake and output; dehydration shows thirst, dry mucosa, sunken eyes, scanty dark urine and fast pulse.
Worked example
A tray contains 60 g carbohydrate, 20 g protein and 10 g fat. Reasoning: 60 × 4 = 240 kcal from carbohydrate; 20 × 4 = 80 kcal from protein; 10 × 9 = 90 kcal from fat. Total = 240 + 80 + 90 = 410 kcal.
Traps that cost marks
Treating fat as 4 kcal/g; prescribing a high-protein diet to a renal patient; restricting fluids without an order; confusing marasmus with kwashiorkor; charting intake in cups without converting to millilitres.