Could B Vitamin Megadoses Increase Actually Lung Cancer Risk For Male Smokers?

Henrietta Strickland
August 23, 2017

Although now, there is evidence of just how much harm long-term mega-supplementation with B6 and B12 can do for male smokers. Vitamins B6 and B12 are also important for healthy nerve function.

For this study, Theodore Brasky, PhD, of the OSUCCC - James, 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 created to evaluate vitamin and other mineral supplements in relation to cancer risk.

Prior studies created to assess the association between lung cancer risk and B vitamin intake have yielded inconsistent results.

"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", he said. Further, the results of this study conflict with the results of previous studies, including a randomized control trial as well as two studies that measured vitamin B6 serum levels and demonstrated reduction in lung cancer risk. Upon enrolling in the study, participants reported information to researchers about B-vitamin usage over the past 10 years.

Brasky and colleagues linked the study cohort to a population-based SEER cancer registry that documented all incident cancers except nonmelanoma skin cancers diagnosed in a 13-county region of western Washington.

Analysis revealed no association among women between lung cancer risk and supplementation with vitamin B6 or vitamin B12.

But there was no similar risk in women who took the supplements.

Brasky said that these findings relate to doses that are well above those from taking a multivitamin every day for 10 years.

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1.3 milligrams is the daily recommended dose for B6 and 2.4 micrograms is the recommended daily dose for B12

The increased risk persisted for all histologic subtypes of lung cancer except adenocarcinoma, for which researchers observed no association. "Our study found that consuming high-dose individual B6 and B12 vitamin supplements over a 10-year period is associated with increased lung cancer risk, especially in male smokers".

A high dose of B12 is considered to be 55 milligrams, but B12 supplements come in doses of up to 5,000 milligrams.

Male smokers who took more than 20mg of B6 a day for 10 years were three times more likely to develop lung cancer than people who did not take supplements.

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.

He warned many vitamin B supplements contained doses which were "much, much higher than the daily recommended amount".

"These are supraphysiological doses that are not necessary for your health", Brasky said.

'It's very easy to get all the vitamin B you need from eating meats, chickpeas and foods like cereal that are fortified with them, so there really is no reason to supplement your vitamin B intake at these levels, and certainly not for years on end, ' he added.

Disclosures: The NCI, NIH and Office of Dietary Supplements funded this study.

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