Vitamins B6 and B12, among the most popular supplements on the market to boost energy, have been linked to an increased risk for lung cancer in men. A new study by Ohio Stae University found men who take too much of the vitamins face far greater cancer risks, especially if they smoke.

“What we found was that men who had used dietary supplements, in particular B6 and vitamin B12, at high doses for 10 years, were at significant increased risk of developing lung cancer,” said Dr. Theodore Brasky, who led the study at OSU's Comprehensive Cancer Center.

“In fact, all men who used these supplements in high doses for a decade had approximately double the risk developing lung cancer, and in men who smoked, the risk was three to four times as great.”

The researchers found no increased risk of lung cancer in women who took high-dose vitamin B6 and B12 supplements long-term, only men.

The recommended daily allowance for vitamin B6 for men is only about one and a half milligrams, and for vitamin B12, it’s less than two and a half micrograms per day.

“But if you look at these supplement bottles, they’re being sold in pill form at up to 5,000 micrograms per dose, which is much, much higher than the daily recommended amount,” said Brasky. “It’s very easy to get all the vitamin B you need in this country, 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.”

The study tracked more than 77,000 patients for more than a decade.