Antioxidants are nature’s defense against harmful molecules known as ”free radicals,” which are constantly produced by the body as cells carry out their functions. These unstable molecules can damage our cells and lead to diseases such as cancer as we age.
While some antioxidants are produced by the body, others – like beta-carotene from carrots, lycopene from tomatoes, and polyphenols from grapes – are obtained through an individual’s diet. All of these antioxidants are believed to prevent and limit cell damage, or ”oxidative stress,” caused by free radicals.
But with all of their benefits, is it possible to have too many antioxidants?
Research has shown that people who consume a diet rich in antioxidant-rich fruits, vegetables, and legumes tend to have a lower risk of cardiovascular disease, cancer, and early death from any cause. It may seem like increasing your antioxidant intake – through supplements, for example – would be beneficial. However, compared to food, supplements make it easier to exceed the recommended doses of antioxidants, which can actually be harmful.
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Side effects of high doses of antioxidants range from mild to very serious. On the milder end, excessive amounts of beta-carotene can turn the skin yellow or orange, which is visually striking but not harmful. Excessive vitamin C intake can lead to digestive issues, such as diarrhea, nausea, and abdominal cramps.
More seriously, high doses of beta-carotene may increase the risk of lung cancer and cardiovascular disease in individuals already at high risk for these diseases, such as current and former smokers and people who have been exposed to asbestos. There is also evidence from studies of animals and human tissue suggesting that antioxidants can promote the growth and spread of some cancers.
In addition, high-dose vitamin E supplements have been shown to interact with certain medications, such as aspirin, warfarin, tamoxifen, and cyclosporine A. They have also been linked to an increased risk of early death in people with chronic disease.
These studies suggest that, yes, having excessive amounts of antioxidants can be harmful – but why? One reason is that low levels of free radicals can actually be beneficial.
“There is a lot of evidence indicating that free radicals have beneficial roles in physiological processes,” Ismail Laher, a professor of pharmacology at the University of British Columbia, told Live Science in an email. At low concentrations, free radicals help cells grow and are part of the body’s defense mechanism against disease. They are also involved in the metabolism, or breakdown, of drugs and participate in cell-to-cell communication.
There is such a thing as too much of a good thing. While antioxidants have numerous health benefits, excessive intake can disrupt the delicate balance in our bodies. Moderation is key!