Vitamin B12

What it is

Vitamin B12 (cobalamin) is a water-soluble vitamin essential for red blood cell formation, neurological function, and DNA synthesis. It is found almost exclusively in animal foods, so supplements are important for vegans, older adults, and those with absorption problems.

Benefits

Supplementation prevents and treats B12 deficiency, which can cause anemia and irreversible nerve damage if untreated. While the RDA is just 2.4 mcg, oral supplements commonly use much higher doses (about 250-1,000 mcg) because only a small fraction is absorbed, especially in older adults or those with low stomach acid.

When to take it

Taken daily, with or without food; people with absorption issues may need high-dose oral, sublingual, or injectable forms regardless of timing.

Side effects

Very safe with no established upper limit because excess is excreted; injectable forms may cause mild reactions. Deficiency is the real risk in vegans, older adults, and people with pernicious anemia or gut disorders, who may need injections.

Sources

• NIH ODS Vitamin B12 Fact Sheet for Health Professionals

Products containing Vitamin B12

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