Food, Nutrition and Health
What this domain tests
MATSEC Intermediate Home Economics asks you to move between nutrient science and the plate: name sources and functions of nutrients, apply Dietary Reference Values (DRVs) to real diets, and judge claims made by food marketers and the media.
Core rules
- Energy: Atwater factors - protein 4 kcal/g, carbohydrate 4, fat 9, alcohol 7 (1 kcal = 4.184 kJ).
- DRV family: EAR (average requirement for a group), RNI (EAR + 2SD, covers about 97.5% of people), LRNI (intake below which deficiency is almost certain), Safe Intake where data are insufficient.
- Adult reference intakes: total fat ≤35% of food energy, saturates ≤11%, free sugars ≤5% (SACN, 2015), salt ≤6 g/day, fibre 30 g/day, 5 A DAY = 400 g fruit and vegetables.
- Protein RNI for adults is 0.75 g per kg body weight; needs rise in pregnancy, lactation and growth.
- Micronutrients that matter locally: iron (haem vs non-haem; vitamin C aids absorption, phytates and tannins inhibit it), calcium and vitamin D, folate (400 µg before conception), iodine, B12 for vegans.
Worked example
A sedentary 60 kg woman eating 2,000 kcal/day. Protein RNI = 0.75 × 60 = 45 g/day. Fat ceiling: 35% of 2,000 = 700 kcal ÷ 9 = 78 g. Saturates: 11% = 220 kcal ÷ 9 = 24 g. Free sugars: 5% = 100 kcal ÷ 4 = 25 g. The reasoning that earns marks is that percentages refer to energy, never to food weight, and each conversion divides by that nutrient's kcal per gram - a step candidates routinely invert.
Traps that cost marks
- Quoting an RNI when the question asks for an EAR (group average vs individual cover).
- Giving fat limits in grams without stating the energy intake they derive from.
- Reading "low fat" as "low energy" - check the sugar.
- Confusing a labelling Reference Intake (an adult average) with a personal DRV.