Food, Nutrition and Health
Food, Nutrition and Health tests nutrients, their functions and sources, deficiency signs, and the link between diet and health. You must distinguish food groups and use nutrient knowledge to judge a diet.
Core concepts
- Macronutrients: carbohydrates and fats give energy; proteins build and repair the body. Micronutrients: vitamins and minerals regulate and protect; water and fibre support digestion and health.
- Energy values: 1 g carbohydrate = 4 kcal, 1 g protein = 4 kcal, 1 g fat = 9 kcal.
- Food groups: energy-giving (cereals, roots, fats, sugar), body-building (pulses, milk, eggs, meat, fish), protective (fruits, vegetables, milk).
- Deficiency examples: vitamin A and night blindness; iron and anaemia; iodine and goitre; vitamin D or calcium and rickets; vitamin C and scurvy; protein-energy malnutrition and kwashiorkor or marasmus.
- Health is not merely absence of disease; a balanced diet, safe water, hygiene and activity support it.
Worked example
A snack has 20 g carbohydrate, 5 g protein and 5 g fat. Energy = (20 x 4) + (5 x 4) + (5 x 9) = 80 + 20 + 45 = 145 kcal. Reasoning: multiply each nutrient by its energy value, then add. The snack is not nutritionally empty if it also supplies vitamins or fibre, so judge the whole diet, not one figure.
Traps
Calling fat unnecessary; forgetting that excess protein is not stored as protein; mixing deficiency diseases; assuming a costly food is always more nutritious; ignoring the loss of water-soluble vitamins during cooking.