Antioxidant Supplements

National Academy of Sports Medicine
National Academy of Sports Medicine
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By Sam Hutchison BS, NASM-CPT

In today’s culture, antioxidants have become synonymous with healthy living. They can be seen in sports drinks, energy bars and supplements which are marketed to provide better health and function. Antioxidants can also be found in natural foods like berries, whole grains, dark chocolate and some vegetables (1).

It is important tounderstand how antioxidants function so that there can be optimal benefits. For this to happen, oxidative stress must be understood.

You can find more information on supplements in the NASM online nutrition course on the subject. Browse all nutrition courses here

What is oxidative stress?

Oxidative stress is a process that occurs within all of us one way or another. This can occur through environmental factors such as smoking, UV light radiation, and exposure to chemical toxins as well as within the body such as acute exercise. It is the process taking an electron from an oxygen molecule causing it to become unstable. These unstable molecules are called free radicals. Due to the loss of an electron, that unstable oxygen molecule seeks electrons from cells within the human body (i.e., to pair with another molecule in order to return to a stable structure) (2). This process subsequently damages the structures of these cells, leading to the effects of aging and disease.

It is antioxidants role to neutralize these free radicals and allow the damaged components to be repaired (2).  Antioxidants are synthesized within the body or they are received from our nutrition including ascorbic acid (vitamin C), glutathione (made in our bodies from the amino acid cysteine), and flavanols/flavonoids (compounds found in plant sources), which are found in an assortment of whole foods and supplements (1).

Read also: Supplements for COVID

Choosing Wisely

Although the benefits of antioxidants seem extraordinary and claims to their benefits are everywhere, they are only one piece of the puzzle.  Certain amounts of oxidative stress are necessary in order for our body to adapt to environmental stressors. Acute exercise produces a healthy amount of oxidative stress necessary to signal changes within the body such as the creation of new cell structures, bodily antioxidant stimulation and insulin sensitivity (2). These significant events can be inhibited by antioxidant supplementation.  A 2008 study showed that endurance athletes who took Vitamin C supplements demonstrated lower rates of mitochondrial production, and fewer improvements in VO2max and in time to exhaustion tests after an eight week training protocol (3).  This study provided evidence supporting the belief that antioxidant supplementation may interfere with the signaling process needed for these events to provide significant benefit.

Another study conducted was one that looked into a more diseased population. A seven year study was conducted to measure the effects of a vitamin C supplement on blood glucose levels (4). This study was designed to determine whether antioxidants had an effect on diabetes prevention. In the end, researchers found inconclusive evidence that vitamin C supplementation had an effect on reducing the free radicals thought to cause high blood glucose levels in diabetes.

Although some research may not support the benefits of supplementing antioxidants, the benefits of antioxidants found in natural plant sources should not be omitted from ones diet. Whole foods containing antioxidants have additional components that aid in optimizing how antioxidants are utilized within the body (1, 5).

In closing, although antioxidants may provide health benefits, buying supplements can become an expensive venture, even when purchased occasionally. It is important to have an understanding of their function within the body, follow research not advertising claims, and recognize the differences between antioxidants attained from supplements versus whole foods. The importance of understanding the general concepts of antioxidants can help someone become well informed of what their exact purpose is within the body and make proper health choices.

If this subject has piqued your interest, and you want to learn more about the various goals and strategies you can implement with supplementation, consider becoming a Nutrition Specialist with NASM.


  1. Insel P., Ross D., McMahon K., et al. Nutrition. 4th ed. Sudbury, MA: Jones and Bartlett; 2011.
  2. Farrell PA, Joyner MJ, Caiozzo VJ. ACSM’s Advanced Exercise Physiology 2nd ed. Baltimore, MD: Lippincott, Williams & Wilkins; 2012.
  3. Gomez-Cabrera MC, Domenech E, Romagnoli M, Arduini A, Borras C, Pallardo FV, Sastre J, Vina J. Oral administration of vitamin C decreases muscle mitochondrial biogenesis and hampers training-induced adaptations in endurance performance (2008) Am J Clin Nutr; 87:142-149
  4. Czernichow S, Couthouis A, Bertrais S, Vergnaud AC, Dauchet L, Galan P, Hercberg S Antioxidant supplementation does not affect fasting plasma glucose in the Supplementation with Antioxidant Vitamins and Minerals (SU.VI.MAX) study in France: association with dietary intake and plasma concentrations. (2006) Am J Clin Nutr; 84(2):395-399
  5. National Institute of Health. Antioxidants and Health: An Introduction (2010) U.S. Department of Health and Human Services.

Sam Hutchison BS, NASM-CPT is the Content Development Coordinator at the National Academy of Sports Medicine. He is a graduate of Northern Arizona University where he ran track for two years and was named to the Big Sky Academic All-Conference team. He majored in Exercise Science with a minor in chemistry.

The Author

National Academy of Sports Medicine

National Academy of Sports Medicine

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