Men on high doses of vitamin B6 and B12 supplements run a higher risk of lung cancer, and the association is strongest among current smokers, a study published yesterday revealed.
The study uncovered a 30 per cent to 40 per cent increased risk of lung cancer among men taking these vitamins from individual supplements, not from multivitamins or diet alone. The effect, however, seemed to be due to current smokers who far exceeded the recommended daily amounts of the vitamins, according to study author, Theodore Brasky, an epidemiologist in the division of cancer prevention and control at the Ohio State University College of Medicine.
"I think these results point to a synergism" between high-dose B vitamins, smoking and lung cancer risk among men, Brasky said, CNN reported.
Current male smokers who take the highest amounts of vitamin B6 run three times the risk of lung cancer over six years, as against those who did not take supplements. The risk nearly quadrupled for vitamin B12. These levels were over 11 times the recommended daily amount of B6 and 23 times that of B12.
"If you look at B-vitamin supplement bottles ... they are anywhere between 50-fold the US recommended dietary allowance (to) upward of 2,100-fold," Brasky said. B12 injections have also become "in vogue" in recent years, he said.
''This sets all of these other influencing factors as equal, so we are left with a less confounded effect of long-term B6 and B12 super-supplementation,'' Brasky said in a press release. ''Our data show that taking high doses of B6 and B12 over a very long period of time could contribute to lung cancer incidence in male smokers. This is certainly a concern worthy of further evaluation.''
Vitamins B6 and B12 have been touted for their potential to accelerate metabolism and increase energy, and there has also been speculation of the vitamins reducing cancer risk.