Supplement analysis backed by scientific evidence · PT

← All supplements
Strong evidenceGeneral health

Vitamin B12

Essential for red blood cells and the nervous system. Supplementation is clearly effective — and often necessary — for vegans, older adults, and people with absorption problems.

What the science says

  • Correcting and preventing deficiency Strong evidence

    B12 deficiency causes anemia and neurological damage that can become irreversible if untreated. Oral supplementation reliably corrects deficiency, including at high oral doses as an alternative to injections in most people.

  • Essential for vegans and many older adults Strong evidence

    B12 occurs naturally only in animal foods, so supplementation is the standard recommendation for vegans. Up to 20% of older adults absorb food-bound B12 poorly (atrophic gastritis) and benefit from supplements or fortified foods.

  • Energy boost in people with normal levels Limited evidence

    Despite the marketing, there is no good evidence that extra B12 improves energy or cognition in people who are not deficient.

Dosage & safety

Studied doseAdults need only 2.4 mcg/day, but because absorption of large doses is inefficient, supplements commonly provide 250–1,000 mcg/day (cyanocobalamin or methylcobalamin — both work).
SafetyVery safe; excess is excreted. No established upper limit. Deficiency should be confirmed and monitored with blood tests.

Scientific references

Where to buy

Life Extension, Vitamin B12, Methylcobalamin, 500 mcg, 100 Vegetarian Lozenges

View on iHerb

Referral link — this site may earn a commission on purchases.

Related in General health