Vitamin B12 (Cobalamin)
Essential for nerves, blood formation, and methylation. Deficiency is common — in vegans and with age (absorption declines) — and, untreated, can cause irreversible nerve damage.
How it works
Vitamin B12 is an essential coenzyme for blood formation, nerve function (myelin sheaths) and methylation metabolism (homocysteine clearance). Since it's found almost only in animal foods, supplementation is mandatory on a plant-based diet. Deficiency develops slowly but can cause lasting nerve damage.
Dosage
Vegans and older adults: supplement regularly. Methyl- or cyanocobalamin both work. Measure status (holo-TC, possibly methylmalonic acid).
Considerations
One of the few genuinely essential supplement cases: deficiency is real and common — practically guaranteed on a fully plant-based diet, with age via declining stomach acid/intrinsic factor, and on metformin or acid blockers (PPIs). Untreated, anemia and irreversible neurological damage can follow. The rule: measure and correct deliberately, don't megadose blindly.
