Do Folic Acid and B12 Cause Cancer?

Excess cancer incidence and cancer mortality occurred in a follow-up of two clinical trials of folic acid and B₁₂ supplements for cardiovascular risk reduction.

Two recent prospective, randomized clinical trials in Norway were designed to assess cardiovascular risk reduction from supplementation with folic acid (0.8 mg/day) and vitamin B₁₂ (0.4 mg/day), with or without vitamin B₆ (40 mg/day), in patients with ischemic heart disease. As in other secondary-prevention trials, the supplements did not reduce cardiovascular events or mortality, but folic acid plus B₁₂ was associated with a statistically nonsignificant increase in cancer rate over a mean of 39 months. This finding prompted the current analysis of data on 6837 patients followed for 3 years after the trials were completed.

During the trials and follow-up period, those randomized to folic acid plus vitamin B₁₂ (but not B₆) had an excess risk …

Reviewing Author

Laurence J. Kinsella, MD

Do Folic Acid and B₁₂ Cause Cancer?

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Reviewing Author