(Ivanhoe Newswire) -- Common antioxidants you take to improve your health may actually increase your risk of dying.

A new report contradicts the claims of previous studies that antioxidant supplements, like beta-carotene, vitamin A, and vitamin E, prevent diseases. Researchers analyzed previous research, which included 68 randomized trials and 232,606 participants. The authors classified the trials based on the quality of the methods used in the study, identifying high quality trials as "low-bias risk" and low quality trials as "high-bias risk."

Antioxidants decrease the damage free radicals cause in the body. Free radicals are unstable, reactive chemicals. They can be created in the body or be introduced into the body from the environment. Free radicals have been linked to cancer and heart disease.

Researchers report no significant association between antioxidant use and death when researchers analyzed all low-bias and high-bias trials. In 47 low-bias trials, which included 180,938 participants, the supplements were associated with a 5 percent increased risk of mortality. In the low-bias studies, beta-carotene, vitamin A and vitamin E were associated with 7 percent, 16 percent, and 4 percent increased risk of mortality, respectively. There was no increased risk associated with vitamin C or selenium.

Researchers report beta-carotene, vitamin A, and vitamin E alone or combined with other antioxidant supplements significantly increases mortality. There is no evidence vitamin C can help people live longer.

"Our findings contradict the findings of observational studies claiming that antioxidants improve health," write the authors. "Considering that 10 percent to 20 percent of the adult population (80 million to 160 million people) in North America and Europe may consume the assessed supplements, the public health consequences may be substantial. We are exposed to intense marketing with a contrary statement, which is also reflected by the high number of publications per included trial found in the present review."

The authors write there are several possible explanations. Eliminating free radicals from our bodies may interfere with some of the ways we keep ourselves healthy.

SOURCE: The Journal of the American Medical Association, 2007;297:842-857