High-Dose Vitamins B6 and B12 Increase Lung Cancer Risk

Long-term high-dose B6 and B12 vitamin supplement use is thought linked to lung cancer risk. Men taking them for more than 10 years had 2-4 times more lung cancer than nonusers, particularly smokers. No similar increase was found in women.

This notable study appeared on 22 August in the Journal of Clinical Oncology. It suggests prolonged high-dose B6 and B12 vitaminsmay accelerate lung cancer occurrence in male smokers.

The United States National Institutes of Health Office of Dietary Supplements states that men over 51 need 1.7 mg daily, women 1.5mg, of B6; for B12, the recommended adult dose is 2.4 µg daily.

The study examined men taking B vitamins, with B6 over 10 years at 20 mg daily and B12 at 55 µg.

Study Details

Participants aged 50-76, totaling 77.118, were enrolled between October 2000 and December 2002. Over 10 years, 808 developed lung cancer.

More than half (%55) were men. Researchers investigated supplement use among lung cancer patients. Questionnaires covered supplements, diet and smoking. An association between B vitamins and lung cancer occurred in men but not women; high-dose users had almost 2 times the risk of nonusers.

In this study, male smokers using high-dose B6 had up to 3 times greater lung cancer risk, while B12 increased risk up to 4 times.

Analysis adjusted for smoking history, age, race, education, body size, alcohol, personal cancer or chronic lung disease history, family lung cancer history and anti-inflammatory medicine use.

The increase only among male smokers is striking. Researchers suggest different susceptibility between men and women to tobacco-related lung cancer and androgen effects on certain enzymes as possible explanations. High-dose B6 and B12 may accelerate cell growth, promoting proliferation of mutated cells in male smokers.

Warning for Supplement Users

Half of United States adults use one or more dietary supplements. Despite unproven benefits, products marketed as promoting healthy living are increasingly used in developing societies including ours… Remember: no vitamin or mineral supplement should be taken without a blood-test-confirmed deficiency.

In conclusion, high-dose B6 and B12 use beyond 10 years increased lung cancer risk, particularly in male smokers. Similar earlier findings with antioxidants showed they do not treat cancer and may even promote it.

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