Long-term use of supplemental vitamins B6, folate, and B12 have been linked to a significant increase in lung cancer risk particularly in men who smoke, according to the Vitamins and Lifestyle (VITAL) cohort.
B vitamins are among the most popular dietary supplements on the market in the U.S. Some, like B6 and B12, are often promoted by the dietary supplement industry as energy and metabolism boosters. But epidemiologists from The Ohio State University Comprehensive Cancer Center, Fred Hutchinson Cancer Research Center and National Taiwan University reported in the Journal of Clinical Oncology that these vitamins are associated with a two- to four-fold increased lung cancer risk compared to men who did not take the supplements.
The risk was even greater among men who smoked who took more than 20 mg of B6 or 55 micrograms of B12 a day for 10 years. Male smokers who took more than 20 mg of B6 were three times more likely to be diagnosed with lung cancer, and those taking 55 mcg of B12 were about four times more likely to develop the disease compared to comparable men who did not take the vitamins.
The study is the first prospective, observational study to look at how long-term use of high-dose B6 or B12 supplements affect lung cancer risk, and turns the tables on the long-held notion that the B vitamins help reduce cancer risk.
Researchers are planning two additional studies to better understand the link between high-dose, long-term B6 and B12 vitamin supplement use and lung cancer. One study will examine whether this risk is similar in post-menopausal women. The other will be a second large prospective study in men taking high-dose, long-term B6/B12 supplements to see if the study results are replicated.
MPR Science Daily