Antioxidants and Sports NUtrition

This happens quite often in the world of Nutrition as well as Sport that a word gets thrown around without complete understanding of what that word or term is.  Today that word is Antioxidant.  Without diving too far into the chemistry and biochemistry of how antioxidants work, antioxidants protect against free radicals or reactive oxygen species (ROS).  The chemical structure of free radicals allow them to go around the body ‘stealing’ electrons from healthy cells in the body causing damage.  Antioxidants go around the body finding these free radicals and donate electrons to the free radicals to protect the body.  The body begins to get damaged when the free radicals overwhelm the antioxidant defenses.

In the world of athletics and sport, exercise can increase the presence of free radicals by 10-15% then a normal person.  This increase in free radical production may result in increased fatigue, muscle damage and reduced immune function.  In response to this it’s fairly logical to increase intake of foods with a higher amount of antioxidants such as Vitamin C, Vitamin E, Carotenoids and Flavonoids (colour pigments and metabolites from vegetables, respectively), but does this actually help? And does this additional supplementation improve athletic performance?

In a 2005 study by Watson et al. it was found that in a group eating a high antioxidant diet vs. one that was eating an antioxidant deprived diet that oxidative stress was higher in the restricted group.  However, in another study by Watson et al. supplementing athletes with Vitamin E actually increased oxidative stress! In another study by Peternelj & Coombes (2011), the researchers found loading cells with antioxidants produced a ‘blunting’ of the benefits of exercise and interfered with the beneficial aspects of ROS, which include vasodilation and insulin signaling. 

A study by Clarkson and Thompson (2000) and Paulsen et al (2014) showed that additional antioxidants were needed to prevent oxidative stress in athletes but did not find any positive impact on athletic performance.  They also found that exercise training appears to reduce the oxidative stress of exercise in trained athletes when compared to the general population. This finding was also supported by Draeger et al. (2014).  Finally, Lamina et al. (2013) and Marin et al. (2013) found that overtraining causes increase oxidative stress. 

It is recommended by researchers that athletes eat a minimum of 2-3 servings of fruit and 4-5 servings of vegetables per day to ensure a diet high in antioxidants.  In all cases researchers recommended that antioxidants be consumed through the diet rather then through supplementation.  In fact antioxidants from whole foods resulted in the optimal ratio in the body vs supplementary sources of antioxidants.  So yes, athletes do require more antioxidants to adapt to the stressors of training but they should be consumed through whole foods as opposed to supplements.  You may be asking at this point, what foods have antioxidants in them? Well the best food sources of antioxidants include wheat, barley, sprouts, dark green vegetables, blueberries, blackberries, strawberries and any food high in Vitamin E, Vitamin C, Beta-Carotene, Selenium and Flavonoids. 

The bottom line? Eat your fruits and vegetables! Choose from a variety of fruits and vegetables while looking at the entire colour spectrum.  Different colours indicate different nutrients, vitamins and minerals, so eat a large variety to get all your bases covered.  Put down that bottle of mega-dosed vitamins that aren’t doing you any good.  Eat more fruits and vegetables and let your body optimize the amount of antioxidants it needs as opposed to doing a supplemental blitzkrieg! And in more severe cases of fatigue, muscle damage or impaired immune function go see a Sports Dietitian to help best optimize your nutritional intake for athletic performance and optimal health! 


Ben Sit, RD, Sports Dietitian 


References 


Clarkson, P. M., & Thompson, H. S. (2000). Antioxidants: what role do they play in physical activity and health? American Journal of Clinical Nutrition , 72 (2), 637-646.

Cox, G. (n.d.). Antioxidants in sport: current thinking. Retrieved June 21, 2014, from Australian Sports Commission: https://secure.ausport.gov.au/sports_coach/nutrition2/antioxidants_in_sport_current_thinking

Draeger, C., Naves, A., Marques, N., Baptisella, A., Carnauba, R., Paschoal, V., et al. (2014). Controversies of antioxidant vitamins supplementation in exercise: ergogenic or ergolytic effects in humans? Journal of the International Society of Sports Nutrition , 11 (4).

Gliemann, L., Schmidt, J., Olesen, J., Bienso, R., Peronard, S., Grandjean, S., et al. (2013). Resveratrol blunts the positive effects of exercise training on cardiovascular health in aged men. Journal of Physiology , 591, 5047-5059.

Lamina, S., Ezema, C. I., Theresa, A. I., & Anthonia, E. U. (2013). Effects of free radicals and antioxidants on exercise performance. Oxidants and Antioxidants in Medical Science , 2 (2), 83-91.

Marin, D. P., Bolin, A., Compoio, T., Guerra, B., & Otton, R. (2013). Oxidative stress and antoixidant status response of handball athletes: Implications for sport training monitoring. International Immunopharmacology , 17, 462-470.

Paulsen, G., Cumming, K. T., Holden, G., Hallen, J., Ronnestad, B. R., Sveen, O., et al. (2014, Feb). Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double-blind randomized controlled trial. Journal of Physiology .

Peternelj, T.-T., & Coombes, J. S. (2011). Antioxidant Supplementation during Exercise Training: Beneficial or Detrimental? Sports Medicine , 41 (12), 1043-1069.