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Many athletes I work with ask me about taking probiotic supplements. But are they really necessary? We’ll get into that, but first let me explain what probiotics are.
We are all born with a collection of microbes, or microscopic organisms, which include bacteria, viruses, fungi, protists, archaea, and microscopic animals. These microbes are our first line of defense against invading germs. We have certain species of these bacteria living in our mouth, skin, nose, and gut. Over the last several years, much of the microbe research has been focused on the role that our gut microbiome (collection of these microbes) plays in our overall health – the results are fascinating! Of all the parts of our body, the most important and complex habitat of microbes is in our gut – the live bacteria in our guts are known as probiotics.
Probiotics are friendly gut bacteria that keep our gastrointestinal tract and our gut microflora healthy and happy. Their functions include converting fiber into short chain fatty acids, synthesizing certain vitamins, and supporting a healthy immune system (Clemente et al. 2012). Other research suggests that a healthy microbiota population may decrease the risk of allergies (Round et al. 2009), the behavioral symptoms of autism (Vuong et al. 2017), and the symptoms associated with digestive disorders, such as Crohn’s disease and inflammatory bowel disease (Spor et al. 2011).
Eating and taking probiotic supplements can help increase the number of beneficial bacteria in your gut. Foods that contain natural probiotics include fermented vegetables, such as kimchi and sauerkraut, fermented soybeans, such as miso and tempeh, fermented tea, called kombucha, and kefir and yogurt with live, active cultures. Probiotics can also be purchased and taken as a dietary supplement.
Now, we are back to our question – should athletes take a probiotic supplement? The answer is, it depends! Heavy exercise, especially endurance type exercise is associated with an increased risk of upper respiratory infections (URI), as well as gastrointestinal (GI) tract symptoms, such as bloating, nausea, and diarrhea (Pugh et al. 2018). Several studies investigating the effect of probiotic supplements on the prevention of upper respiratory tract infections in athletes have shown promising results (Pyne et al, 2015). In one study, athletes who were administered a probiotic supplement for one month reported less than half the number of days of respiratory symptoms than the placebo group. Illness severity was also lower for episodes occurring during the supplementation period (Cox et al. 2010). Another study in which 84 active individuals consumed either a probiotic or placebo supplement for 16 weeks showed that subjects in the probiotic group had substantially fewer upper respiratory illnesses with 36% fewer subjects reporting illness compared with the control group (Gleeson et al. 2011).
In a 2015 study, researchers found that subjects (mice) with a greater diversity of intestinal flora lasted longer in swim-to-exhaustion tests, and the mice also produced a greater amount of antioxidant enzymes that decrease the physiological stresses associated with intense physical activity (Hsu et al. 2015). Another study on highly trained men found that supplementation with probiotics for 14 weeks decreased markers for impaired gut barriers, decreased inflammatory markers, and decreased oxidative stress markers (Lamprecht et al. 2012).
During strenuous activity, bad bacteria can leak from the gut into the bloodstream to trigger inflammation and raise core temperatures, which reduces the body’s tolerance to hot and humid environments. Probiotics can improve the health of the gut lining to reduce leakage and control inflammation. In one study, researchers found that probiotics helped runners perform better on a treadmill in 95-degree heat. Participants in this study who took probiotics were able to exercise longer than the subjects who did not take the supplements (Shing et al. 2014).
Based on the comprehensive research on gut health, all athletes should increase their intake of food sources containing probiotics. In addition, these types of athletes should consider adding in a high-quality probiotic supplement:
If you need more information on probiotic supplementation or on which product to buy, do not hesitate to reach out at Allison@altnutrition.net.
Clemente, J. C., Ursell, L. K., Parfrey, L. W., & Knight, R. (2012). The impact of the gut microbiota on human health: an integrative view. Cell, 148(6), 1258-1270.
Cox, A. J., Pyne, D. B., Saunders, P. U., & Fricker, P. A. (2010). Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes. British Journal of Sports Medicine, 44(4), 222-226.
Gleeson, M., Bishop, N. C., Oliveira, M., & Tauler, P. (2011). Daily probiotic’s (Lactobacillus casei Shirota) reduction of infection incidence in athletes. International journal of sport nutrition and exercise metabolism, 21(1), 55-64.
Hill, C., Guarner, F., Reid, G., Gibson, G. R., Merenstein, D. J., Pot, B., ... & Calder, P. C. (2014). Expert consensus document: The International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nature Reviews Gastroenterology and Hepatology, 11(8), 506.
Hsu, Y. J., Chiu, C. C., Li, Y. P., Huang, W. C., Te Huang, Y., Huang, C. C., & Chuang, H. L. (2015). Effect of intestinal microbiota on exercise performance in mice. The Journal of Strength & Conditioning Research, 29(2), 552-558.
Lamprecht, M., Bogner, S., Schippinger, G., Steinbauer, K., Fankhauser, F., Hallstroem, S., ... & Greilberger, J. F. (2012). Probiotic supplementation affects markers of intestinal barrier, oxidation, and inflammation in trained men; a randomized, double-blinded, placebo-controlled trial. Journal of the International Society of Sports Nutrition, 9(1), 45.
Pugh, J., Kirk, B., Fearn, R., Morton, J., & Close, G. (2018). Prevalence, Severity and Potential Nutritional Causes of Gastrointestinal Symptoms during a Marathon in Recreational Runners. Nutrients, 10(7), 811.
Pyne, D. B., West, N. P., Cox, A. J., & Cripps, A. W. (2015). Probiotics supplementation for athletes–clinical and physiological effects. European journal of sport science, 15(1), 63-72.
Round, J. L., & Mazmanian, S. K. (2009). The gut microbiota shapes intestinal immune responses during health and disease. Nature reviews immunology, 9(5), 313.
Shing, C. M., Peake, J. M., Lim, C. L., Briskey, D., Walsh, N. P., Fortes, M. B., ... & Vitetta, L. (2014). Effects of probiotics supplementation on gastrointestinal permeability, inflammation and exercise performance in the heat. European journal of applied physiology, 114(1), 93-103.
Spor, A., Koren, O., & Ley, R. (2011). Unravelling the effects of the environment and host genotype on the gut microbiome. Nature Reviews Microbiology, 9(4), 279.
Vuong, H. E., & Hsiao, E. Y. (2017). Emerging roles for the gut microbiome in autism spectrum disorder. Biological psychiatry, 81(5), 411-423.
Allison Tropf, MS, RD, CSSD
Allison is a Sports Dietitian in Michigan. She enjoys helping others reach their nutrition and fitness goals through reliable and trustworthy recommendations.
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