Food, Nutrition and Health
Food, Nutrition and Health is the science core of the elective: what each nutrient does, how much the body needs across ages, and how food choices show up as health or deficiency disease. Expect questions on nutrient classification, energy calculation, deficiency mapping, food groups and dietary guidelines, food safety and malnutrition.
Nutrient classes and energy
Carbohydrate, protein and fat are energy-yielding macronutrients; vitamins and minerals are protective micronutrients; water is the medium in which body reactions occur. Energy factors: 4 kcal/g for carbohydrate, 4 kcal/g for protein, 9 kcal/g for fat, 7 kcal/g for alcohol (not a nutrient).
Deficiency mapping
Thiamine deficiency gives beriberi; niacin gives pellagra (dermatitis, diarrhoea, dementia); vitamin C gives scurvy; vitamin A gives night blindness and xerophthalmia; vitamin D gives rickets in children and osteomalacia in adults; iodine gives goitre; iron gives microcytic anaemia. Protein-energy malnutrition splits into marasmus (severe wasting, no oedema) and kwashiorkor (oedema, low serum albumin, often in a child recently weaned).
Worked example
A snack supplies 25 g carbohydrate, 8 g protein and 6 g fat. Energy = (25 × 4) + (8 × 4) + (6 × 9) = 100 + 32 + 54 = 186 kcal. The reasoning: convert each macronutrient mass with its own factor, then total. Never use 4 kcal/g for fat, and do not count vitamins or minerals, since they supply no energy.
Traps
Oedema means kwashiorkor, not marasmus; fat is 9 kcal/g; vitamins are needed in micrograms but are still essential; discarding rice-cooking water or overboiling vegetables leaches B-vitamins and vitamin C; a balanced diet means proportion and variety, not simply a high-calorie diet.