Nutrition Science and Medical Nutrition Therapy
This domain tests nutrient requirements, diet modification, malnutrition risk, and medical nutrition therapy across the lifecycle and in disease. Expect calculations, diet-order interpretation, and allergy or dysphagia safety.
Core rules and concepts
- Energy values: carbohydrate 4 kcal/g, protein 4 kcal/g, fat 9 kcal/g, alcohol 7 kcal/g.
- Protein baseline for healthy adults is about 0.8 g/kg/day. Higher intakes, often 1.2–1.5 g/kg/day, may be used in stress, wounds, or recovery, with clinical monitoring.
- Diet progression commonly moves from clear liquid to full liquid to mechanical soft to regular. Clear liquid is not nutritionally complete and is short-term.
- Dysphagia orders use IDDSI levels for food texture and liquid thickness. Follow the speech-language pathologist's order; never guess.
- Therapeutic modifications include sodium restriction for hypertension or heart failure, carbohydrate counting for diabetes, potassium and phosphorus control for renal disease, and allergen avoidance for food allergy.
Worked example
An 80 kg patient is ordered 1.2 g protein/kg/day. Protein = 80 × 1.2 = 96 g/day, or 96 × 4 = 384 kcal. If the diet is 1,800 kcal, protein provides 384 ÷ 1,800 = 21.3% of kcal. If the patient also receives 1,200 mL of a 1.0 kcal/mL formula, that is 1,200 kcal; with 600 kcal of oral intake, total intake is 1,800 kcal. The goal is met only if tolerance and fluid limits allow.
Traps that cost marks
- Treating clear liquid as complete nutrition.
- Missing a renal or cardiac restriction when reviewing a diet order.
- Thickening liquids without an order.
- Ignoring cross-contact risk in food allergy.
- Assuming a supplement replaces food rather than supplements it.