Antioxidant supplements are often touted as a means of preventing disease and fighting the negative effects of aging. Found naturally in a number of foods, antioxidants are substances that help knock out free radicals (chemical byproducts known to damage cells and contribute to the development of certain diseases). Antioxidant supplements may include a number of different free-radical-fighting compounds.
Vitamins in Antioxidant Supplements
Antioxidant supplements often contain the following substances, all of which are considered antioxidants:
- beta-carotene
- lutein
- lycopene
- selenium
- vitamin A
- vitamin C
- vitamin E
Benefits of Antioxidant Supplements
Proponents of antioxidant supplements suggest that increasing your antioxidant intake can help prevent chronic diseases, including heart disease and cancer. But while research shows that a diet high in antioxidant-rich fruits and vegetables can help protect against disease, it remains unclear whether antioxidant supplements are equally effective in disease prevention. What's more, some studies indicate that antioxidant supplements may pose some health risks.
Are Antioxidant Supplements Harmful?
Here's a look at several study findings on the health risks linked to intake of antioxidant supplements:
1) Antioxidant Supplements and Cancer
Regular intake of supplements containing beta-carotene may increase cancer incidence and cancer deaths among smokers, according to a systematic review and meta-analysis published in 2008. The same report also showed that selenium supplementation may have cancer-fighting effects in men, while vitamin E supplementation had no effect on cancer incidence and mortality.
2) Antioxidant Supplements and Cancer Therapy
In a report published in 2008, researchers cautioned that cancer patients should avoid use of antioxidant supplements during radiation and chemotherapy. According to the report's authors, antioxidant supplements may reduce the anticancer effects of therapy.
3) Antioxidant Supplements and Increased Risk of Death
Taking antioxidant supplements containing beta-carotene, vitamin E, and vitamin A may be linked to an increased risk of death, according to a 2007 review and meta-analysis of 68 trials including a total of 232,606 participants. Although no increased mortality risk was associated with vitamin C supplementation, researchers didn't find any evidence that vitamin C supplements increased longevity either. Selenium supplementation, meanwhile, appeared to reduce the risk of death.
Should You Take Antioxidant Supplements?
Some medical experts argue that studies showing a potential health risk for antioxidant supplements have been flawed in design. For instance, after the publication of the 2007 review and meta-analysis linking antioxidant supplements to an increased risk of death, researchers from the Linus Pauling Institute at Oregon State University released a statement arguing that the study is "ignores the broad totality of evidence that comes to largely opposite conclusions." The statement's authors also note that intake of antioxidants from foods or supplements has been shown to reduce risk of cardiovascular disease, some types of cancer, eye disease, and neurodegenerative disease (as well as strengthen the immune system).
For help in boosting your antioxidant consumption, start by adding more antioxidant-rich foods to your diet. (Learn about the best food sources of antioxidants.)
If you're looking to further increase your intake of antioxidants, talk to your doctor about whether antioxidant supplements are right for you.
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