Link uncovered between heavy vitamin B intake and lung cancer in men

23 Aug 2017 --- Vitamins B6 and B12 have been long touted by the vitamin industry for increasing energy and improving metabolism, and possibly even reducing cancer risk. However, new research suggests that long-term, high-dose supplementation is associated with a two- to four-fold increase in lung cancer risk in men relative to non-users. This is the first prospective, observational study to look at the effects of long-term high-dose B6/B12 supplement use and lung cancer risk. 

Lung cancer risk was further elevated in male smokers taking more than 20mg of B6 or 55mg of B12 a day for ten years. Male smokers taking B6 at this dose were three times more likely to develop lung cancer, while male smokers taking B12 at such doses were approximately four times more likely to develop the disease compared to non-users.

The study, conducted by epidemiologists from The Ohio State University Comprehensive Cancer Center - Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC - James), Fred Hutchinson Cancer Research Center and National Taiwan University, was published in the Journal of Clinical Oncology.

For this study, Theodore Brasky, Ph.D., and colleagues analyzed data from more than 77,000 patients participants in the VITamins And Lifestyle (VITAL) cohort study, a long-term prospective observational study designed to evaluate vitamin and other mineral supplements in relation to cancer risk. All participants were aged between 50 and 76 were recruited in the state of Washington between the years 2000 and 2002. Upon enrolling in the study, participants reported information to researchers about B-vitamin usage over the past ten years. This included dosage information – a critical but often missing detail needed for strong risk assessment and association research.

For this new analysis, researchers used statistical techniques to adjust for numerous factors including personal smoking history, age, race, education, body size, alcohol consumption, personal history of cancer or chronic lung disease, family history of lung cancer and use of anti-inflammatory drugs.

“This sets all of these other influencing factors as equal, so we are left with a less confounding effect of long-term B6 and B12 super-supplementation,” Brasky says. “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.”

Brasky notes these findings relate to doses that are well above those from taking a multivitamin every day for ten years.

“These are doses that can only be obtained from taking high-dose B vitamin supplements, and these supplements are many times the US Recommended Dietary Allowance,” he says.