Male smokers taking 20 milligrams of vitamin B-6 per day for 10 years were three times more likely to go on to develop lung cancer, while male smokers taking 55 micrograms of vitamin B-12 per day for 10 years were around four times more likely to develop the disease. For vitamin B12, that risk almost quadrupled.
Brasky and team are now conducting two more studies, one to see whether the results are repeated in another similarly large, prospective study of men and the other to examine the association among post-menopausal women, to confirm the current finding that women are not at any increased risk.More news: United States open for discussion with North Korea: Rex Tillerson
The researchers determined that men who now smoked and reported taking more than 20 milligrams (mg) of vitamin B6 daily during the 10-year period leading up to the study were about three times as likely to develop lung cancer than current smokers who didn't use B6 supplements at all.
Researchers said there was no increased risk of lung cancer in women who took high doses of vitamin B. We found that men who took high doses of vitamin B6 and B12 from individual supplements over a long period of time (meaning, doses much higher than the US RDA and much greater than what one would receive from taking a multivitamin over the long term) were at almost 2-fold increased risk of lung cancer compared to men who did not have B6 or B12 intake from any supplemental source. To date, results have been inconclusive - this is partly because the trials were rarely randomized, they investigated only short periods of supplementation, and only small numbers of lung cancer cases were involved in the analysis. There also has been speculation that these vitamins may reduce cancer risk. Male smokers taking B12 at such doses were approximately four times more likely to develop the disease compared to non-users.
It's also possible that this action from the B vitamins simply hastens the development of an underlying lung tumor already caused by smoking, Brasky says. Some were quick to point out that other studies find vitamin B to be beneficial for lung cancer. Long-Term, Supplemental, One-Carbon Metabolism-Related Vitamin B Use in Relation to Lung Cancer Risk in the Vitamins and Lifestyle (VITAL) Cohort. We were unable to address whether lung cancer patients had improved or worsened prognosis if they took these supplements.More news: Walmart Teams With Google On Voice Activated Shopping
Although the associations weakened among recent and former smokers who reported the highest usage of both vitamins, the HRs for lung cancer risk in both groups remained greater than 1.
Disclosures: The NCI, NIH and Office of Dietary Supplements funded this study. "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", Brasky said. The researchers report no relevant financial disclosures.More news: Navy ships keep getting into accidents. Time to find out why