Nutrition and Health
What this domain tests
Nutrition and Health tests nutrient function, energy balance, dietary guidelines, diet-related disease and the interpretation of food labels. Expect calculations and questions that ask you to justify dietary advice for a named life stage or health condition.
Core rules and concepts
- Energy values: protein 4 kcal/g, carbohydrate 4 kcal/g, fat 9 kcal/g and alcohol 7 kcal/g. In kilojoules, the values are approximately 17, 16, 37 and 29 kJ/g.
- A balanced diet supplies energy and nutrients in the proportions shown in Healthy Food for Life, Ireland’s food pyramid: plenty of vegetables, salad and fruit; wholemeal cereals and breads; moderate dairy and protein foods; small amounts of fats, spreads and oils; and no more than very small amounts of treats.
- Adults should eat at least five portions of fruit and vegetables a day and keep free sugars below 10% of energy, ideally below 5%. Saturated fat should provide less than 10% of energy, and salt should be limited to about 6 g a day.
- RDAs are population intake recommendations; NRVs are label reference values used on packaging. They are not individual prescriptions.
Worked example
A meal contains 20 g protein, 60 g carbohydrate and 30 g fat. Calculate its energy and the percentage of energy from fat.
Protein: 20 × 4 = 80 kcal. Carbohydrate: 60 × 4 = 240 kcal. Fat: 30 × 9 = 270 kcal. Total = 590 kcal. Fat percentage = 270 ÷ 590 × 100 = 45.8%. This is well above the guideline that fat should provide no more than about 35% of energy, so the meal is high in fat and the advice would be to reduce added fat and choose leaner cooking methods.
Traps that cost marks
Do not mix kcal and kJ; 1 kcal equals about 4.184 kJ. Do not state that a “fat-free” label makes a food nutritious, because it may still be high in sugar or salt. Match deficiencies to the correct nutrient, such as iron with anaemia and calcium with rickets.
Key points
- Protein and carbohydrate supply 4 kcal/g; fat supplies 9 kcal/g.
- Free sugars should be under 10% of energy, ideally under 5%.
- Saturated fat should supply less than 10% of energy.
- NRVs on labels differ from individual RDAs.
- Convert kcal to kJ by multiplying by approximately 4.184.