Can Probiotics Improve Athletic Performance?

More than 100 trillion different microbes live in your gut. Gut microbiota (GM) is found mostly in the colon and consists of bacteria, viruses, fungi and protozoa. It is known that GM break down fiber, produces vitamin K, and aids in pathogen recognition. However, gut microbiota’s influence on exercise performance is only beginning to be understood. Understanding how exercise effects GM, how GM effects endurance performance, and how diet can promote gut health may improve your athletic performance.

Resent research has shown a link between exercise and changes in GM. People who regularly engage in endurance exercise have a greater gut microbial diversity compared to sedentary individuals. A more diverse GM is characteristic of a thriving gut flora, and is associated with an increase in the benefits afforded by a healthy GM.

GM effects energy metabolism, immune response, oxidative stress, and hydration status, and thus effects endurance performance. The relationship between GM and energy metabolism has just begun to be researched.  It is known that carbohydrate fermentation is a major function of GM and facilitates energy and carbon metabolism in the colon. Complex polysaccharides are digested and fermented by GM into short-chain fatty acids (SCFAs). The SCFAs are absorbed thru the colon and used as energy sources by liver and muscle cells which increases available energy during endurance performance. The amount of SCFAs produced is determined by GM composition. Also, periods of relative energy deficiency that occur during endurance exercise have been shown to cause changes in GM composition. These changes in GM could potentially be used as biomarkers for overtraining in athletes.

An unhealthy GM composition has been associated with inflammatory changes that increase gut wall permeability. This allows for migration of bacterial out of the gut and may lead to immune system dysfunctions. Alter GM has been associated with asthma, eczema, environmental allergies, and increased upper respiratory infections. Intense training reduces blood flow to the digestive organs which also leads to inflammation and increased gut wall permeability. A thriving GM may be protective against inflammation and gut “leaking” caused by intense exercise. Supplementing with probiotic has been shown to reduce the number and severity of upper respiratory tract infections in athletes.

During intense exercise, the activity of antioxidant enzymes becomes weaker and catecholamine production increases. Both increase reactive oxygen species (ROS), nitrogen oxide species (RONS), and oxidative stress. Increased oxidative stress reduces athletic performance and increases recovery time. Initial research has shown that redox homeostasis is related to a balanced GM composition. Thus, a healthy GM may promote athletic performance by reducing oxidative stress.

 Fluid losses from sweating during endurance exercise can lead to dehydration which decreases performance. Intestinal mucosa has a primary role in electrolyte and water transport. A protective intestinal barrier of GM is believed to be necessary for intestinal mucosal hydration function. Proper GM function has been associated with maintaining better hydration during exercise.

Maintaining a healthy GM may improve endurance performance and is a fairly simple process. Evidence has shown consuming probiotics regularly positively changes GM. Probiotics are live microorganisms contained in foods or supplements. The best probiotic contains several microbial strains, including lactobacillus and bifidobacterium. Food sources of probiotics are fermented foods, like kombucha, kimchi, and sauerkraut, or cultured dairy products such as butter milk, kefir, and yogurt.

References

Clark, A., & Mach, N. (2016). Exercise-induced stress behavior, gut-microbiota-brain axis and diet: a systematic review for athletes. J Int Soc Sports Nutr, 13, 43. doi:10.1186/s12970-016-0155-6

Mach, N. (2017). Endurance exercise and gut microbiota: A review. Journal of Sport and Health Science, 6, 179- 197. doi.org/10.1016/j.jshs.2016.05.001

O'Sullivan, O., Cronin, O., Clarke, S. F., Murphy, E. F., Molloy, M. G., Shanahan, F., & Cotter, P. D. (2015). Exercise and the microbiota. Gut Microbes, 6(2), 131-136. doi:10.1080/19490976.2015.1011875

Rankin, A., O’Donavon, C., Madigan, S. M., O’Sullivan, O., & Cotter, P. D. (2017). ‘Microbes in sport’ – The potential role of the gut microbiota in athlete health and performance. British Journal of Sports Medicine, 51(9), 698-699. doi:10.1136/bjsports-2016-097227