Vitamin B12

Tier 2 — promising · Vegans · Elderly · Cognition

Essential for nerve myelin synthesis, DNA production, and red blood cell formation. About 20% of adults over 60 and 50%+ of vegans are deficient. Deficiency causes fatigue, megaloblastic anaemia, and — if prolonged — irreversible peripheral neuropathy and cognitive decline. A 2024 Cochrane review (Finkelstein, 5 RCTs, 984 pregnant women, PMID 38189492) confirmed B12 supplementation during pregnancy reduces maternal deficiency risk by 62%. Absorption declines markedly with age (gastric atrophy reduces intrinsic factor). Sublingual or methylcobalamin forms bypass intrinsic-factor dependency.…

Dose: 500-1,000 mcg/day oral or sublingual methylcobalamin or cyanocobalamin. Deficiency correction: 1,000 mcg/day for 1-3 months. Confirm deficiency with serum B12 plus methylmalonic acid (MMA) — MMA is more sensitive.