Men who take vitamin B6 and B12  as individual supplements may increase their risk of lung cancer, according to a study published in the Journal of Clinical Oncology.1

Increased vitamin B intake is hypothesized to interfere with the one-carbon metabolism pathway, a process that is thought to be important for gene expression regulation and DNA integrity maintenance, thereby increasing carcinogenic risk. Previous trials investigating the association of increased risk of lung cancer and vitamin B supplementation have returned mixed results.

For the VITAL cohort, researchers assessed the responses of 77,118 participants who reported their intake of multivitamins, individual vitamin supplements, and any vitamin mixtures, and calculated the prior-to-study 10-year average daily doses for vitamin B6, B9, and B12.

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The results showed that among women, there was no correlation between supplemental B6, B9, and B12 and lung cancer risk.

Among men, taking B6 and B12 from only individual supplement sources was associated with a 30% to 40% increase in risk for lung cancer.

The risk of lung cancer almost doubled for men who took the highest doses of 10-year average daily dose of vitamin B6 (> 20 mg/day; hazard ratio [HR], 1.82; 95% CI, 1.25-2.65) and vitamin B12 (> 55 μg/day; HR, 1.98; 95% CI, 1.32-2.97), compared to non-users.

The risk nearly tripled (HR, 2.93; 95% CI, 1.50-5.72; P = .04) and quadrupled (HR, 3.71; 95% CI, 1.77-7.74; P < .01) in men who were current smokers who took vitamin B6 and B12 at the highest levels, respectively (P < .01), compared to male smokers who did not take B6 or B12 supplements.

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The authors of the study concluded that “the associations we observed provide enough evidence that high-dose B6 and B12 supplements should not be taken for lung cancer prevention and, in fact, may increase risk of this disease in men.”

Editors note: This article has been corrected to reflect that lung cancer risk nearly tripled and quadrupled in men who were current smokers and taking B6 and B12 at the highest levels compared to male smokers who did not take B6 or B12 supplements.


  1. Brasky TM, White E, Chen CL. Long-term, supplemental, one-carbon metabolism–related vitamin B use in relation to lung cancer risk in the vitamins and lifestyle (VITAL) cohort. J Clin Oncol. 2017 Aug 22. doi: 10.1200/JCO.2017.72.7735