Scenario: A 58 year-old man named Mike has just been diagnosed with prostate cancer. He is wondering how this could be since there is no family history of the disease, and he exercises regularly, is a vegan, and takes antioxidant supplements. Mike assumed that his healthy lifestyle would decrease his chances of developing cancer, but apparently not. After talking to his doctor, he wonders if the supplements played a causal role in his recent diagnosis.
Antioxidants are substances that protect against the detrimental effects of oxygen free-radicals. These radicals, with reactive, unpaired electrons, are produced during normal metabolism and can damage cell membranes and biological molecules such as protein or DNA. Diets high in fruits and vegetables are rich in antioxidants, such as vitamin C, vitamin E, β-carotene and selenium, which can neutralize these reactive oxygen species. Many people, however, do not consume adequate amounts of these foods. This explains why the dietary supplement industry promotes antioxidant supplements to consumers, with promises of decreasing aging and preventing cancer along with other health-promoting properties. This sounds great, of course, but is there any scientific proof to back up these claims?
According to the National Institutes of Health (NIH), supplements with high doses of β-carotene may increase the risk of lung cancer in smokers and vitamin E supplements may increase the risk of hemorrhagic stroke and prostate cancer. In 2011, a study of >35,000 men, known as The Selenium and Vitamin E Cancer Prevention Trial (SELECT), discovered that selenium and vitamin E supplements did not decrease the risk of prostate cancer, and that vitamin E supplements (taken alone) increased the risk by 17% (NCCAM Supplements). Multiple other studies echo these findings (Harvard University). Nonetheless, many people in the USA continue to regularly use antioxidant supplements, according to experts at Stanford University (Stanford University).
One possible reason for antioxidant supplements doing more harm than good relates to the fact that high levels of antioxidants can potentially convert to proxidants. Moreover, oxidant molecules are used in the body to get rid of damaged cells, including those that are precancerous or cancerous, so supplements could disrupt an important oxidant/antioxidant balance. So as the saying goes, more is not always better.
The best option for obtaining adequate amounts of antioxidants is adding fruits, vegetables, and whole grains to your diet. The typical American diet already provides 120% of the RDAs for many antioxidant nutrients (JNCI Paper), so supplementation should not be necessary for most healthy people. Furthermore, the health-promoting benefits of consuming antioxidant-rich foods may actually be caused by other substances present in the same foods, or relate to lifestyle choices of individuals who most often consume these foods.
Conclusion to Scenario: In the end, Mike realizes that not every claim about dietary supplements is true. Mike does not want what happened to him to also happen to his little brother. He thus intends to warn his little brother about the truth behind antioxidant supplementation. What will you do? We suggest you get the facts, and only the facts, before using any dietary supplement.
(Written with the creative assistance of Nehemie Laguerre, a University of Florida undergraduate student)