Antioxidants are man-made or natural substances that may prevent or delay some types of cell damage. Diets high in vegetables and fruits, which are good sources of antioxidant, have been found to be healthy; however, research has not shown antioxidant supplements to be beneficial in preventing diseases. Examples of antioxidants include vitamins C and E, selenium, and carotenoids, such as beta-carotene, lycopene, lutein, and zeaxanthin.
There is good evidence that eating a diet that includes plenty of vegetables and fruits is healthy and official Government policy urges people to eat more of these foods. Research has shown that people who eat more vegetables and fruits have lower risks of several diseases; however, it is not clear whether these results are related to the amount of antioxidants in vegetables and fruits, to other components of these foods, to other factors in people’s diets or to other lifestyle choices.
Rigorous scientific studies involving more than 100,000 people combined have tested whether antioxidant supplements can help prevent chronic diseases, such as cardiovascular diseases, cancer and cataracts. In most instances, antioxidants did not reduce the risks of developing these diseases.
Concerns have not been raised about the safety of antioxidants in food. However, high-dose supplements of antioxidants may be linked to health risks in some cases. Supplementing with high doses of beta-carotene may increase the risk of lung cancer in smokers. Supplementing with high doses of vitamin E may increase risks of prostate cancer and one type of Antioxidant supplements may stroke.[i] Antioxidant supplements may also interact with some medications.
Free radicals are highly unstable molecules that are naturally formed when you exercise and when your body converts food into energy. Your body can also be exposed to free radicals from a variety of environmental sources, such as cigarette smoke, air pollution and sunlight. Free radicals can cause “oxidative stress,” a process that can trigger cell damage. Oxidative stress is thought to play a role in a variety of diseases including cancer, cardiovascular diseases, diabetes, Alzheimer’s disease, Parkinson’s disease and eye diseases such as cataracts and age-related macular degeneration.
There is debate as to whether consuming large amounts of antioxidants in supplement form actually benefits health. There is also some concern that consuming antioxidant supplements in excessive doses may be harmful.[ii] Like some other dietary supplements, antioxidant supplements may interact with certain medications. For example, Vitamin E supplements may increase the risk of bleeding in people who are taking anticoagulant drugs (blood thinners). There is conflicting evidence on the effects of taking antioxidant supplements during cancer treatment; some studies suggest that this may be beneficial, but others suggest it may be harmful. The National Cancer Institute recommends that people who are being treated for cancer talk with their health care provider before taking supplements.
Science, Studies and Trials
Several decades of dietary research findings suggests that consuming greater amounts of antioxidant-rich foods might help to protect against diseases. Observational studies have provided ideas about possible relationships between dietary or lifestyle factors and disease risk, but cannot show one factor causes another because they cannot account for other factors that may be involved. People who eat more antioxidant-rich foods might also exercise or may not smoke therefore it may be that these factors, rather than diet alone might account for their lower disease risk.
Researchers have also studied antioxidants in laboratory experiments which showed the antioxidants interacted with free radicals and stabilized them, thus preventing the free radicals from causing cell damage.
Because of these studies and results, there has been much research on antioxidant supplements. However, rigorous trials of antioxidant supplements in large numbers of people have not found that high doses of antioxidant supplements prevent disease.
The Age-Related Eye Disease Study (AREDS), led by the National Eye Institute did find a beneficial antioxidant supplements effect, which showed a combination of antioxidants (vitamin C, E and beta-carotene) and zinc reduced the risk of developing the advanced stage of age-related macular degeneration by 25 percent in people with the intermediate stage of this disease or who had the advanced stage Antioxidant supplements used alone reduced the risk by in only one eye.[iii] Antioxidant supplements used alone reduced the risk by about 17 percent. In the same study, however, antioxidants did not help to prevent cataracts or slow their progression. To help prevent eye diseases, antioxidants that are present in the eye, such as lutein, might be more beneficial than those that are not found in the eye, such as beta-carotene.
It would appear that eating your fruits and vegetables is the best intake of antioxidants for your health as differences in the chemical composition of antioxidants in foods versus supplements may influence their effects. For example: 8 chemical forms of vitamin E are present in foods. Vitamin E supplements typically include only one of these forms and is used in almost all research studies on vitamin E.
As always, consult Dr. Greif and all health practitioners before taking any supplements. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.
[i] Gaziano JM, Glynn RJ, Christen WG, et al. Vitamins E and C in the prevention of prostate and total cancer in men: the Physicians’ Health Study II randomized controlled trial JAMA. 2009;301(1):52-62.
[ii] Jerome-Morais A, Diamond AM, Wright ME. Dietary supplements and human health: for better or for worse? Molecular Nutrition & Food Research. 2011;55(1):122-135.
[iii] Christen WG, Glynn RJ, Chew EY, et al. Vitamin E and age-related macular degeneration in a randomized trial of women. Ophthalmology 2010; 117(6): 1163-1168.