VitaminNo.007
Vitamin B12
Nerve health, red blood cells, energy metabolism.
Typical / RDA2.4 mcg
Upper limitNone set
EvidenceStrong
How to take it
Timing MorningFood OptionalForm Methyl-/cyanocobalamin
What to know
Found almost only in animal foods, so plant-based eaters and many older adults (reduced absorption) are at real risk. No established upper limit. Prolonged deficiency can cause irreversible nerve damage.
Interactions & cautions
- Metformin and long-term acid reducers lower B12 — monitor if you take them.
Often worth it
Vegan, vegetarian, or 50+? Strong candidate for supplementation.
Reference values: NIH Office of Dietary Supplements, adult general population. Educational information only — not medical advice. Confirm with a healthcare professional.