A new study, published Tuesday in the Journal of Clinical Oncology, has found a link between high doses of vitamin B6 and B12 supplements and increased lung cancer risk, especially among men who smoke.
Researchers recruited more than 77,000 adults ages 50-76 in Washington and collected data on the participants’ vitamin use over the past 10 years, including dosage information.
They found that the risk nearly doubled for non-smoking men taking the vitamin supplements, tripled for male smokers taking high doses of B6 and quadrupled for male smokers consuming high doses of B12.
“Our data shows that taking high doses of B6 and B12 over a very long period of time could contribute to lung cancer incidence rates in male smokers. This is certainly a concern worthy of further evaluation,” lead study author and Ohio State University professor Theodore Brasky said in a statement.
Male smokers taking more than 20 milligrams of B6 or 55 micrograms of B12 daily for 10 years had the highest lung cancer risk.
These doses were more than 11 times the recommended daily amount of B6 — and 23 times that of B12.
Women were not at greater risk, according to the study.
Previous studies on the subject vary in their findings. Some have linked B6 with a lower risk of lung cancer, and another found B12 had no impact on lung cancer risk whatsoever, CNN reported.
But the observational study does not prove cause-and-effect — only an association between the vitamin supplements and lung cancer.
The Council for Responsible Nutrition, an industry trade group, urged readers not to make a causal connection and instead take away the fact that cigarette smoking is still the most important factor in lung cancer risk.
Researchers are currently working to study the relationship between the vitamin supplements and lung cancer risk with a larger participant group.
Read the full study here.