Food, Nutrition and Dietetics
Food, Nutrition and Dietetics examines how food supplies nutrients, how needs change across life stages and how diets are modified for health. The exam tests nutrient functions, energy calculation, balanced diets, food groups, deficiency conditions and basic therapeutic diet planning.
Core rules and concepts
- Energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g; alcohol supplies 7 kcal/g. Convert kilocalories to kilojoules using 1 kcal = 4.184 kJ.
- Protein quality depends on the essential amino acid pattern and digestibility. Cereals are limited in lysine; pulses are limited in methionine, so combining them improves protein quality.
- A balanced diet supplies energy and all nutrients in amounts suited to age, sex, activity and physiological state. Variety alone does not guarantee balance; quantity and proportion matter.
- Dietary fiber is non-digestible carbohydrate. Soluble and insoluble fibers have different effects, so fiber is not one substance.
- Therapeutic diets modify consistency, energy, protein, sodium, fiber or a specific nutrient rather than simply reducing food intake.
Worked example
A snack contains 40 g carbohydrate, 10 g protein and 10 g fat. Energy = (40 × 4) + (10 × 4) + (10 × 9) = 160 + 40 + 90 = 290 kcal. For a 1,500 kcal prescription, the snack supplies 290 ÷ 1,500 × 100 ≈ 19% of daily energy. The reasoning links grams of each nutrient to its energy factor, then expresses the item as a proportion of the prescribed total.
Traps that cost marks
Do not use 9 kcal/g for protein or 4 kcal/g for fat. Do not label every anaemia as iron deficiency: vitamin B12 and folate deficiencies also cause anaemia. Do not call a diet balanced merely because it contains many foods. Do not confuse gross energy with metabolizable energy.