Nutrition Science Fundamentals
What this domain tests
Nutrition Science Fundamentals tests whether you can explain nutrient classification, digestion and absorption, energy yield of macronutrients, and how dietary reference intakes guide recommendations. Expect items on kcal per gram, essential versus nonessential nutrients, and the difference between RDA, AI, UL, and AMDR.
Core rules
- Energy yield: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g, alcohol 7 kcal/g; fermentable fiber contributes roughly 2 kcal/g.
- Essential nutrients include 9 amino acids, 2 fatty acids (linoleic and alpha-linolenic), 13 vitamins, minerals, and water.
- DRI family: EAR is the median requirement; RDA covers 97–98% of healthy people; AI is used when an RDA cannot be set; UL is the tolerable upper intake; AMDR is a population range (carbohydrate 45–65%, fat 20–35%, protein 10–35%).
- Digestion: carbohydrate starts in the mouth with salivary amylase, protein in the stomach with pepsin, fat is emulsified by bile; most absorption occurs in the small intestine.
- Nutrient density describes nutrients per kcal; energy density describes kcal per gram.
Worked example
A snack contains 20 g carbohydrate, 10 g protein, 8 g fat, and 3 g alcohol. Calculate 20×4 + 10×4 + 8×9 + 3×7 = 80 + 40 + 72 + 21 = 213 kcal. If the label rounds to 210 kcal, that is expected. If a client reports 150 kcal, check whether fiber or sugar alcohols were subtracted incorrectly; sugar alcohols average about 2 kcal/g, not zero.
Traps that cost marks
Using 9 kcal/g for protein, forgetting alcohol’s 7 kcal/g, treating an AI as an RDA, assuming the AMDR is an individual target, and confusing EAR with RDA. Also remember that essentiality is about the body’s inability to synthesize enough, not about food source.