A recently reported clinical study suggests that there may be a link between heavy vitamin B6 and B12 supplementation and lung cancer in men, especially men who smoke. The researchers report that the risk is two to four times greater for long-term users of the supplements compared to non-users.
The study analyzed data for just over 77,000 participants, age 56-70, in the VITamins And Lifestyle (VITAL) cohort study, a long-term observational study that examined the association between vitamin and mineral supplementation and cancer risk. Participants reported their vitamin B usage, including dosage information, for the 10-year period prior to the study.
The research team found the highest risk for male smokers taking more than 20 mg of B6 or 55 micrograms of B12 a day for 10 years. Male smokers taking B6 were at three times greater lung cancer risk; those taking B12 were at four times greater risk. Non-smoking men were at twice the risk as those not taking the supplements. Women were not found to be at greater risk.
The study accounted for a range of factors that could influence the outcome, including age, race, education, alcohol consumption, body mass, and family history of lung cancer. With these and additional factors weighed in, the risk remained high for men taking high doses of the supplements, particularly smokers.
The recommended daily intake of vitamin B6 is 1.3 milligrams in men and women ages 19-50; 1.7 milligrams in men aged 51 and older; and 1.3 milligrams in women aged 51 and older, according to the National Institutes of Health. For B12 the recommended daily amount is 2.4 micrograms for ages 14 and older. The amounts of both vitamins associated with cancer risk in this study were significantly higher than the government’s recommendations.
This was an observational study; the findings are a correlation, but not proof of causation. The data however suggest that taking high doses of B6 and B12 over a prolonged period could contribute to lung cancer in male smokers.
Brasky T, White E and Chen C-L. Long-Term, Supplemental, One-Carbon Metabolism–Related Vitamin B Use in Relation to Lung Cancer Risk in the Vitamins and Lifestyle (VITAL) Cohort. DOI: 10.1200/JCO.2017.72.7735 Journal of Clinical Oncology – published online before print August 22, 2017