Vitamin E Supplements May Raise Lung Cancer Risk

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Since the primary cause of lung cancer is smoking, the best preventive measure is simply not to smoke, Jacobs said. Nutrients can play an auxiliary role, he noted. Anyone who cannot quit should avoid taking beta-carotene supplements, because studies have linked them to an increased risk of lung cancer, Jacobs said.

On the other hand, "for former smokers, there is some evidence that vegetables high in carotinoids, such as carrots and sweet peas, decrease the risk," he said.

Some vitamins have been linked to a reduced risk of other cancers, added Edward Gorham, an associate professor of family and preventive medicine at the University of California at San Diego.

"We have worked with vitamin D, and we found a protective effect of vitamin D on colon cancer, breast cancer and ovarian cancer, and recently a modest effect on lung cancer," Gorham said.

But that effect came not from supplements but from sunlight, which causes vitamin D to be formed in the human body, he said.

"These results with multivitamins dont surprise me because there is so little vitamin D in multi-supplements, 100 or 200 International Units," Gorham said. "To achieve the effect, it takes 2,000 IU. If youre in the tropics, that amounts to 10 or 15 minutes in the sun. In southern California, it takes 10 or 15 minutes in the summer and longer in the winter because the sun angle is so low."

One study has also associated vitamin D supplements with a decreased risk of colon and breast cancer in women, Gorham said.

More information

There's more on nutrition and cancer prevention at the American Cancer Society.