02/25/08

FINLAND:  Vitamin E Use May Raise Tuberculosis Risk in Heavy Smokers

A new study finds the use of vitamin E supplements could cause some middle-aged smokers to be at higher risk for tuberculosis infection.

Vitamin E is a commonly used dietary supplement thought to enhance immune function, noted Drs. Harri Hemila and Jaakko Kaprio of the University of Helsinki. However, trials in human subjects have shown unpredictable benefits of the vitamin on various infectious diseases. To assess the impact of vitamin E use on TB risk, the researchers analyzed data from the ATBC (Alpha-Tocopherol, Beta-Carotene) Cancer Prevention Study.

The study included 29,023 male smokers ages 50-69. Participants were randomly assigned to take daily supplements containing vitamin E, beta carotene, vitamin E plus beta-carotene or inactive placebo.

During the approximately six years of follow-up, 174 cases of TB were diagnosed. The overall analysis found neither vitamin E nor beta-carotene supplements affected the risk of TB. However, for some, the combination of smoking at least 20 cigarettes per day, consuming diets rich in vitamin C, and taking vitamin E supplements more than doubled the TB risk. Further analysis showed the increased risk was restricted to the first year on vitamin E.

"Although vitamin E may be beneficial in restricted population groups, those groups are poorly defined so far," Hemila and Kaprio noted. "The consumption of vitamin E supplements by the general population should be discouraged because there is evidence of harm for some people," they concluded.

The study, "Vitamin E Supplementation May Transiently Increase Tuberculosis Risk in Males Who Smoke Heavily and Have High Dietary Vitamin C Intake," was published in the British Journal of Nutrition (2008;doi:10.1017/S0007114508923709).

Source: Reuters; Courtesy of the CDC National Center for HIV, STD, and TB Prevention