Smoking, Beta-Carotene Pills a Bad Combo
Stopping Supplements Removes Increased Lung Cancer Risk
July 22, 2003 -- First, the good news for smokers: The increased risk of lung cancer believed to result from taking beta-carotene supplements appears to disappear when the pills are discontinued.
Now, the bad news: Protection against prostate cancer also disappears when vitamin E pills are discontinued.
Last decade, a team of American and Finnish government health officials studied the effects of both supplements on some 25,000 male smokers in Finland. They found that compared with patients taking a placebo, those who consumed a daily beta-carotene supplement had a 17% higher rate of lung cancer, while those taking alpha-tocopherol -- a form of vitamin E -- had a 34% lower risk of prostate cancer, but the nutrient had no real effect on lung cancer rates. That study showed the supplements produced a less significant impact, good or bad, on other forms of cancer.
In this week's Journal of the American Medical Association, they report that in following the surviving patients of that eight-year study for another four to six years, both the beneficial or adverse effects of the two supplements seemed to disappear after the men stopping taking the antioxidant pills -- typically after 18 months.
Translation: Using beta-carotene supplements may be hazardous to a smoker's health, while continuing vitamin E pills may be helpful.
"I certainly would recommend that smokers not take beta-carotene supplements," says study researcher Philip R. Taylor, MD, ScD, of the National Cancer Institute Center for Cancer Research. "For vitamin E, we saw some potential protection against lung cancer toward the end of the study, and our previous study suggested protection against prostate cancer. While it's not proven and needs more study, it is promising."
Bad News for Antioxidants
Taylor's study comes just weeks after a report by the U.S. Preventive Services Task Force, the nation's top independent preventive health group, which says there's insufficient evidence to recommend taking antioxidant pills to prevent either cancer or heart disease. The task force specifically warned against taking beta-carotene supplements.
Exactly how beta-carotene supplements boost lung cancer risk in smokers is not clearly understood. Taylor tells WebMD that in the presence of cigarette smoke and possibly alcohol, beta-carotene may "convert" from having antioxidant properties that destroy disease-causing "free radical" cells to actually inducing or increasing their production.
But another recent study suggests that beta-carotene pills may boost a smoker's risk of colon cancer, as well. In May, John A. Baron, MD, of Dartmouth Medical School, reported in the Journal of the National Cancer Institute that smokers and drinkers who take the supplements may double their risk of colon cancer. However, the supplements reduced risk by about 44% in people who neither smoke nor drink. He isn't surprised by Taylor's new findings.
"There's no reason to think that the effects, good or bad, would continue after the time you take these agents," he tells WebMD. "I don't think anyone ever thought these agents would provide a permanent reduction in risk. But it is reassuring that the risk from beta-carotene didn't persist, either."