NEW YORK (CBSNewYork) -- Could vitamin B supplements protect against lung cancer?
As CBS2's Dr. Max Gomez reported, early studies seemed to show that they might, and they are now some of the most popular supplements sold in drug stores.
But a new study now says the exact opposite might be true.
Six years ago, a French study found that having higher levels of vitamin B6 appears to reduce lung cancer risk.
But naturally having higher levels is not the same as saying that taking lots of B6 or the popular energy vitamin B12 is protective.
In fact, it may be harmful.
In a study that followed more than 77,000 people for more than a decade, researchers noted a troubling trend when it comes to one of the most popular vitamin supplements on the market.
"What we found was that men who had used dietary supplements, in particular B6 and also vitamin B12 were at significant increased risk of developing lung cancer," said Dr. Theodore Brasky of the Ohio State University Comprehensive Cancer Center.
In men who smoked, the risk was three to four times greater, depending on which of the two B vitamins they were taking.
The study looked at both men and women who took high doses for 10 years. A high dose of B6 is considered 20 milligrams, but supplements come in doses of up to 500 milligrams.
A high dose of B12 is considered to be 55 milligrams, but B12 supplements come in doses of up to 5,000 milligrams.
"These are supraphysiological doses that are not necessary for your health," Brasky said.
Researchers at the James Cancer Hospital and Solove Research Institute said it is easy to get plenty of B vitamins from diet – foods like cereals are fortified with them, and some energy drinks have 8,000 percent of the recommended daily allowance of B12.
"I don't think there's a clear, scientific backing for a healthful need for these supplements at those doses," Brasky said.
Although now, there is evidence of just how much harm long-term mega-supplementation with B6 and B12 can do for male smokers.
The high-dose energy drinks are not quite as concerning as supplements, since you likely would not drink those every day for years the way the men in the study had taken supplements. The danger is from long-term, very high-dose B vitamin supplements, not from diet or a daily multivitamin.
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