Food and Nutrition
Food and Nutrition
The Food and Nutrition domain tests whether you can explain what nutrients do in the body, how food is digested and used, and how to plan, prepare, and store meals that are safe, affordable, and suited to different family members. Questions often combine science with practical kitchen decisions.
Nutrients and their jobs
- Macronutrients: carbohydrates (main energy source, 4 kcal/g), proteins (growth and repair, 4 kcal/g), fats (concentrated energy, insulation, 9 kcal/g).
- Micronutrients: vitamins, minerals, and water.
- Fat-soluble vitamins A, D, E, K are stored in the liver and fatty tissue. Water-soluble vitamins B-complex and C are not stored well, so they need a daily supply, and they are lost by heat, long boiling, and leaching into cooking water.
- Deficiencies: vitamin A – night blindness; iron – anaemia; iodine – goitre; calcium and vitamin D – rickets.
- Protein-energy malnutrition: marasmus shows severe wasting without oedema; kwashiorkor shows oedema, a swollen belly, and low protein intake.
Digestion
Starch begins to break down in the mouth (salivary amylase). Protein is digested in the stomach by pepsin in acid conditions. The small intestine is the main site of digestion and absorption, helped by bile emulsifying fat and by pancreatic enzymes; villi increase the absorbing surface. The large intestine absorbs water.
Planning, cooking, and safety
A balanced meal includes an energy food (cereals, starches), a body-building food (legumes, meat, eggs, milk), and a protective food (vegetables, fruit). Keep high-risk foods out of the danger zone between 5 °C and 60 °C, reheat thoroughly, and separate raw and cooked food. Steam, stir-fry, or boil in minimal water to keep water-soluble vitamins; do not add bicarbonate of soda to green vegetables, as it destroys thiamine and vitamin C.
Worked example
A 100 g portion provides 20 g carbohydrate, 10 g protein, and 5 g fat. Energy = (20 × 4) + (10 × 4) + (5 × 9) = 80 + 40 + 45 = 165 kcal. Multiply by 4.2 to convert to kilojoules: about 690 kJ. Always show each nutrient separately before adding.
Traps that cost marks
- Swapping marasmus and kwashiorkor.
- Claiming fat-soluble vitamins are lost in boiling water.
- Confusing kcal with kJ (1 kcal ≈ 4.2 kJ).
- Saying excess protein is stored as protein; excess is used for energy or stored as fat.