Regenerative Processes
This domain addresses tissue repair: wound healing, bone remodelling, muscle protein synthesis, and gut mucosal renewal. The exam tests sequencing and substrate priorities, so candidates must know when nutrition supports repair and when it cannot compensate for poor perfusion, offloading, or drugs.
Wound healing phases and nutrient demands
Haemostasis (platelets, fibrin) gives way to inflammation (neutrophils days 1–3, macrophages days 3–7), proliferation (fibroblasts, angiogenesis, granulation, epithelialization, days 4–21), and remodelling (weeks to months, collagen III replaced by I with cross-linking). Protein needs rise to 1.25–1.5 g/kg/day, higher in burns. Vitamin C is a cofactor for prolyl and lysyl hydroxylase; copper is required by lysyl oxidase for cross-linking; zinc supports epithelialization and immunity; iron supports hydroxylation; vitamin A supports epithelialization.
Bone, muscle, and gut renewal
Bone remodelling runs in cycles of roughly 120 days, with osteoclast resorption followed by osteoblast formation under RANKL control; calcium 1000–1200 mg, vitamin D, vitamin K2 (for osteocalcin carboxylation), magnesium, and adequate protein all contribute. Muscle protein synthesis responds to 20–40 g of high-quality protein per meal and about 2.5 g leucine, amplified by resistance exercise. Colonocytes use butyrate from fibre fermentation; enterocytes use glutamine; sleep and fasting periods support autophagy and turnover.
Worked example
A 72-year-old with a stage 2 pressure injury has albumin 2.9 g/dL, eats about 60% of estimated needs, and takes vitamin E 800 IU daily. Priority one is energy (30–35 kcal/kg) and protein (1.25–1.5 g/kg) plus offloading and perfusion assessment. Add vitamin C 500 mg and zinc 30 mg only if intake or status is inadequate, and stop the high-dose vitamin E, which impairs collagen cross-linking and raises bleeding risk. Reassess in two weeks rather than adding more supplements.
Traps
Reaching for micronutrients before fixing energy, protein, and offloading; leaving high-dose vitamin E or glucocorticoids unaddressed; continuing zinc long term and causing copper deficiency; underfeeding protein in older adults for fear of renal harm without evidence of kidney disease.