“Vitamin B12 (methylcobalamin)?”Here!Vitamin B12
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As a supplement
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A form of vitamin B12 in which the vitamin is bound to a methyl group; it is one of several chemical forms of B12 used in supplements, alongside cyanocobalamin and adenosylcobalamin.
Why it’s used
Taken to maintain normal B12 status, which is needed for red blood cell formation, nerve function, and DNA synthesis, and to correct or prevent deficiency.
What the evidence is for
maintaining B12 status and correcting deficiency.
What the evidence says
NIH ODS recognizes B12 as essential, with well-established roles in nerve and blood cell function; deficiency causes anemia and neurological problems, and oral supplementation is an accepted way to correct low status. Whether methylcobalamin specifically outperforms other B12 forms for general supplementation is less settled than the case for B12 adequacy itself.
Dose studied
2.4–2.8 mcg — adult RDA, rising slightly for pregnancy and lactation, per NIH ODS.
Context
Absorption of oral B12 is limited and depends partly on intrinsic factor, which is why some deficiency treatment protocols use larger oral doses or injections; typical maintenance intakes studied for adults are much smaller than deficiency-treatment doses.
Rumors
Correcting vitamin B12 deficiency, which causes megaloblastic anemia, fatigue, a sore tongue, and numbness and tingling in the hands and feet that can become permanent if it is left untreated.
Supports — establishedhealth and safety evidence
Measured as a biomarker.
- Vitamin B12 Fact Sheet for Health Professionals (Regulatory) · Funding not checked
How much is a reference amount
- 2.4 mcg a dayfor adults 19 and over · Recommended Dietary Allowance
No upper limit has been set — the data was not sufficient to set one, which is a gap in the research rather than a finding about safety.
No UL, on grounds of low toxicity potential. The legacy corpus stored three different B12 ceilings across three rows, one of which (1000 mcg) exists nowhere in the DRI.
Every applicable line is shown because we don’t know which one is yours, and a reference intake is a target for a population, not a threshold for harm.