Nutrition and Dietetics: Nutrients, Deficiencies and Therapeutic Diets
What this domain tests
Nutrition and Dietetics tests nutrients, energy values, balanced diets, deficiency diseases and therapeutic diet modifications. Calculations and food-source matching are common.
Core rules
- Energy: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g. Alcohol provides 7 kcal/g but is not a nutrient.
- A balanced diet supplies energy, protein, fat, vitamins, minerals, fibre and water in appropriate proportions.
- Protein requirement for a healthy adult is about 0.8–1.0 g/kg body weight per day; pregnancy, lactation and growth increase it.
- Iron absorption is enhanced by vitamin C and inhibited by tea, coffee and calcium. Vitamin B12 is found mainly in animal foods.
- Marasmus is severe protein-energy deficiency with marked wasting; kwashiorkor shows oedema, poor growth and low albumin.
- Therapeutic diets: diabetic diet controls refined sugar and total carbohydrate; renal diet restricts sodium, potassium and protein as ordered; hypertension diet is low in salt.
Worked example
A 60 kg adult needs about 0.8 g protein/kg/day. Reasoning: 60 × 0.8 = 48 g protein per day. If the person eats 2,000 kcal, 48 g protein supplies 48 × 4 = 192 kcal, which is about 9.6% of energy-close to the usual 10–15% recommendation. To improve iron intake, pair dal or green leafy vegetables with lemon or guava, and avoid tea with meals.
Traps
- Using 4 kcal/g for fat instead of 9.
- Confusing marasmus with kwashiorkor.
- Saying colostrum should be discarded; it is nutrient- and antibody-rich.
- Adding salt liberally to a renal or hypertensive diet.