Macronutrients and Micronutrients
What the exam tests
This domain tests energy-yielding nutrients, essential micronutrients, digestion and absorption, requirement standards, deficiency and toxicity, and practical food-based recommendations.
Core rules
- Protein and carbohydrate provide 4 kcal/g; fat provides 9 kcal/g; alcohol provides 7 kcal/g.
- Protein RDA is 0.8 g/kg/day for healthy adults; needs rise with aging, pregnancy, and catabolic illness.
- Acceptable macronutrient distribution ranges are carbohydrate 45-65%, fat 20-35%, and protein 10-35% of calories.
- Fiber target is about 25-38 g/day; most adults fall short.
- Essential amino acids and essential fatty acids must come from food.
- Micronutrient bioavailability matters: heme iron is better absorbed than non-heme iron; vitamin C enhances non-heme iron; phytates and tannins inhibit absorption; fat-soluble vitamins A, D, E, and K need dietary fat.
- Use RDA or AI for adequacy and UL for toxicity risk; do not confuse them.
Worked example
A vegan client asks how to meet nutrient needs. Reasoning: assess protein variety (legumes, soy, grains, nuts), use fortified plant milk for B12 and calcium, recommend a reliable B12 supplement (for example 25-100 mcg/day or 1000 mcg several times weekly), pair iron-rich foods with vitamin C, include algae-based omega-3 DHA and EPA, and check zinc and iodine. The reasoning is food first, then targeted supplementation for nutrients with unreliable plant sources.
Traps
- Assuming more micronutrient is better; vitamin A, iron, and zinc have real ULs.
- Ignoring bioavailability when interpreting intake.
- Confusing %DV with RDA.
- Forgetting that alcohol adds calories without nutrients.