Vitamin E won't help, may hurt, cancer study says

Years of popping vitamins offer no protection from lung cancer, and taking vitamin E at high doses for a long time may even elevate the risk, according to a new study led by researchers in Seattle.

The researchers from the University of Washington and elsewhere tracked 77,719 Puget Sound-area adults age 55 to 76 for an average of four years to see whether multivitamins, vitamin C, vitamin E and folate reduced their odds of getting lung cancer, the leading cancer killer in the United States. The answer was no, regardless of how many vitamins they had taken during the previous 10 years.

The findings join growing evidence discounting the benefits of taking vitamins and minerals through pills instead of through food.

The study will appear in the March 1 issue of American Journal of Respiratory and Critical Care Medicine.

Dr. Tim Byers, a professor of preventive medicine at the University of Colorado who wrote an accompanying editorial to the UW study, said it echoes two decades of research that packaged vitamins just can't mimic the beneficial properties of vitamins in foods.

"Are [supplements] doing much good biochemically? Probably not," said Byers, who was not involved in the study.

Dr. Christopher Slatore, the study's lead author and a senior pulmonary medicine fellow at the UW, said he was not surprised by the results.

In fact, current smokers who took the highest doses of vitamin E — at least 215 milligrams a day for 10 years — were 59 percent more likely to get lung cancer than those who did not take any, a difference that was unlikely to be due to chance.

Among everyone in the study, high vitamin E users had a lung-cancer rate of 209 per 100,000 people, compared with 189 for nonusers.

But even at high doses, the potential for harm from vitamin E paled in comparison to the risk from tobacco use alone. A current smoker in the study was 24 times more likely to get lung cancer than a nonsmoker. Cigarette smoking causes 90 percent of all lung cancers, according to the National Cancer Institute, which funded the study.

More than half of American adults take supplements, many in the belief that they help guard against chronic diseases or cancer. But Byers said little scientific evidence bears that out.

In fact, some vitamins may even be harmful. For instance, taking supplements of beta carotene, a compound found in many fruits and grains, has been shown to increase the chances of developing lung cancer. That's despite evidence that people who eat a lot of fruits are less likely to get the disease.

Byers said the paradox probably was because foods contain not only vitamins but other compounds that may somehow work to protect the body.

That's not to say that all supplements are ineffective, particularly when taken to correct deficiencies. Lack of vitamin D, for instance, may weaken the immune system. Folic acid reduces the risk of birth defects if taken by pregnant women, Byers said.

In addition, Byers said studies have suggested that selenium, a mineral with antioxidant properties, may help prevent prostate and lung cancer.

Still, Byers said, early hopes that supplements, including vitamin E, would reduce the risk of several types of cancer have not been definitively borne out by controlled trials.

So for lung cancer at least, UW's Slatore said, people should give up the notion of swallowing pills to better health.

"If you have $100, you'd be better off to spend it on nicotine patches," he said.

Kyung Song: 206-464-2423 or ksong@seattletimes.com