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Written by: Sarah Valois, Ph.D Antioxidants seem to be all the rage but what exactly are they? The first thing to understand is that oxidation is a natural process that occurs when oxygen interacts with molecules and living cells. For example, when an apple is bitten into and left on the counter, it quickly begins to turn brown as a result of oxidation1. The introduction of oxygen in the air to the exposed apple cells is altering the molecular structure of the apple cell components by changing the number of electrons present.
Oxidation in humans is essential and is always occurring in our bodies – breathing oxygen into our lungs and also metabolizing food in our digestive tracts are two simple examples. Conversely, oxidation can also cause damage to healthy cells and turn them into disease causing free radicals unless they are otherwise curtailed by the body’s natural defense mechanisms.
And as with the apple, human aging is a function of oxidation as our hair slowly turns gray and our skin becomes wrinkled over time. Many diseases are also associated with the affects of oxidative stress and long term exposure to free radicals. What’s more, athletes have been shown to produce significantly higher levels of free radicals due to the frequent damaging effects of their intense physical training2.
The good news is that the human body is efficient and produces certain enzymes, peptides and other compounds that act as naturally occurring antioxidants and help fight off disease. Interestingly, all plants contain varying amounts of polyphenolic compounds, which act as their own defense mechanisms against insects, fungus and other bacterial pests. And when we consume these polyphenols that are found naturally in fruits, vegetables and whole grains, our total antioxidant capacity can also increase accordingly. In fact, research has shown that diets rich in fruits and vegetables can reduce the risk of many diseases3,4,5.
To date, several thousand different polyphenols have been identified and sorted into broad classifications6. Some are known as anti-carcinogens while others are recognized as anti-inflammatories and others are simply referred to as antioxidants7,8. So while knowledge of individual polyphenols is relatively nascent, what is known is that these plant compounds appear to work synergistically to provide significant health benefits to humans.
One note of caution, is that plant-based antioxidants are fragile and highly susceptible to oxidation of their own, that is, breakdown caused by extended exposure to heat, light and oxygen. As such, it is important to follow a diet rich in minimally processed, rainbow colored fruits and vegetables, which can help safeguard against the damaging effects of oxidation and free radicals.
1 “How Antioxidants Work: Defending Cells Against Free Radicals and Oxidation” WebMD http://www.webmd.com/food-recipes/features/how-antioxidants-work1 Accessed 5/27/09
2 McArdle, W. et al. Exercise Physiology: Energy, Nutrition & Human Performance 6th Ed. 2007.
3 World Cancer Research Fund/American Institute for Cancer Research. Food, nutrition and prevention of cancer: a global perspective. 1st ed. Washington (DC): American Institute for Cancer Research; 1997.
4 Joshipura, KJ et al. “Fruit and vegetable intake in relation to risk of ischemic stroke” Journal of American Medical Association. 1999. 282(13): 1233-39.
5 Luc Dauchet et al. “Fruit and Vegetable Consumption and Risk of Coronary Heart Disease: A Meta-Analysis of Cohort Studies” Journal of Nutrition 2006. 136:2588-2593
6 Harborne, J.B. Phytochemical Methods: A Guide to Modern Techniques of Plant Analysis 3rd Ed. 1998.
7 Kang, S.-Y. et al. 2003. “Tart Cherry Anthocyanins Inhibit Tumor Development in Apcmin Mice and Reduce Proliferation of Human Colon Cancer Cells” Cancer Letters. 194:13-19.
8 Seeram, N. P. et al. 2001. “Cyclooxygenase Inhbitory and Antioxidant Cyanidin Glycosides in Cherries and Berries” Phytomedicine 8(5): 362-369.