High-Dose Vitamin B Supplements Linked to Lung Cancer Risk in Men, Particularly Smokers

A new study points to an association between use of high-dose vitamin B6 and B12 supplements and an increased risk of lung cancer in men, especially in those who smoke. The research was published in Journal of Clinical Oncology.

Inconsistent evidence has suggested there may be a link between vitamin B supplements and lung cancer, but the current research was the first prospective, observational study to examine this potential association. Over 77,000 patients aged 50 to 76 taking part in the VITamins And Lifestyle (VITAL) study were asked about their history of taking any vitamin supplements over the past 10 years. Researchers then linked these participants to a population-based cancer registry to identify 808 cases of invasive cancer that developed after enrollment.

After controlling for characteristics like age, smoking history, and personal or family history of cancer, the researchers found a 30% to 40% increase in lung cancer risk among men who reported using vitamin B6 or B12 in the form of individual supplements, not multivitamins. When taking average dose into account, the association was even stronger, as men taking the highest doses were nearly twice as likely to develop lung cancer (vitamin B6 hazard ratio, 1.82; vitamin B12 hazard ratio, 1.98).

The increased lung cancer risk with vitamin B6 and B12 was even higher for men who reported they were smokers at baseline. Additionally, there was no association present between the B vitamins and adenocarcinoma, the type of lung cancer less commonly related to smoking, while all other histologic types of lung cancer were associated with B6 and B12 use.

In a press release from The Ohio State University Comprehensive Cancer Center (OSUCCC), researchers emphasized that men should not rush to throw out their multivitamins in light of these findings.

“These are doses that can only be obtained from taking high-dose B vitamin supplements, and these supplements are many times the U.S. Recommended Dietary Allowance,” said lead author Theodore Brasky, PhD, of OSUCCC. The 2-fold cancer risk was observed for men taking a 10-year average dose of at least 20 mg/day of B6 and 55 mg/day of B12, whereas the recommended daily intakes for men aged 51 and older are 1.7 mg and 2.4 mg, respectively, according to the Mayo Clinic.

The study did not find any association between B vitamins and lung cancer risk in women, and the press release indicated a study of post-menopausal women is underway to confirm this finding. Another ongoing study will attempt to replicate the association between long-term supplements of high-dose B6 and B12 and lung cancer risk in men.

In the meantime, the link demonstrated in the current study “provides further evidence that vitamin B supplements are not chemopreventive for lung cancer and may be harmful,” the researchers concluded.