February 20, 2015 | 3 minute read

Although not smoking is by far the best way to reduce your risk of lung cancer, about 1 in 5 women who get lung cancer are nonsmokers according to the National Cancer Institute.

Little is currently known about the role of nutrition in preventing lung cancer in female nonsmokers, but research recently published in the International Journal of Cancer suggests that getting enough vitamin E from foods may lower risk for nonsmoking women, especially those exposed to secondhand smoke. However, vitamin E supplements may increase lung cancer risk in these groups.

This study’s authors used data from 65,000 Chinese women who had never smoked and followed them for an average of 12 years to see if they developed lung cancer. They found that women who consumed enough vitamin E from foods to meet Chinese guidelines at the start of the study had a lower risk of developing lung cancer compared to women who did not consume enough vitamin E.

This study used 14 milligrams (mg) of vitamin E per day as the cutoff for adequate intake since this is what is recommended by the Chinese Nutrient Society. U.S. dietary guidelines currently recommend 15 mg per day for adult women.

The authors were also interested in whether vitamin E had a different effect on women with high vs. low levels of exposure to secondhand smoke. About a third of the women had  high exposure to secondhand smoke, such as by living or working with a smoker. They found that higher vitamin E intake from foods led to a lower risk of lung cancer only in women with high exposure to secondhand smoke. No relationship was found between vitamin E intake and lung cancer for women with low exposure to secondhand smoke.

Vitamin E is an antioxidant and may decrease cancer risk in several ways. Nuts, seeds, and vegetable oils are all good sources of vitamin E and are healthy components of the plant-based diet that AICR recommends for cancer prevention. Fruits and vegetables such as spinach, broccoli, mangoes, and tomatoes also contain vitamin E.

While getting vitamin E from foods protected against lung cancer, vitamin E supplements had the opposite effect. Women who used vitamin E supplements had a higher risk of lung cancer compared to women who did not use supplements. This relationship was only significant in women with high exposure to secondhand smoke.

Lung cancer is the second most common cancer and the leading cause of cancer death among women.

These results reinforce the importance of getting nutrients from foods rather than supplements. Other studies have found similar effects: for example, the SELECT trial found that vitamin E supplements increased prostate cancer risk in men. Likewise, AICR and World Cancer Research Fund research has found that foods containing carotenoids decrease lung cancer risk, while beta carotene supplements increase lung cancer risk in smokers.

AICR recommends that you don’t rely on supplements to protect against cancer.