Can the Gut Affect Your Sports Performance and Results?

This 2020 article highlights the various points summarized below:

The microorganisms in the gastrointestinal tract play a significant role in nutrient absorption, vitamin synthesis, energy harvesting, inflammatory modulation, and host immune response, collectively contributing to human health.

Important factors such as age, birth method, antibiotic use, and diet have been established as formative factors that shape the gut microbiota. However, less described is the role that physical exercise plays, particularly how associated factors and stressors, such as sport/exercise-specific diet, environment, and their interactions, can influence the gut microbiota.

In particular, elite athletes offer remarkable physiology and metabolism (including muscle strength/power, aerobic capacity, energy expenditure, and heat production) compared to sedentary individuals, and provide unique insight into gut microbiota research.

The microbiota indirectly influences various indices of exercise performance, recovery, and disease patterns, such as signaling through myokines and other cytokines, modulating the activation of the hypothalamic-pituitary-adrenal axis, and affecting metabolic pathways associated with performance.

According to findings, the amount of exercise (reported weekly exercise time) positively correlated with a higher abundance of the Prevotella genus (≥2.5%). The increased abundance of Prevotella, common in non-Western populations and associated with plant/fiber-rich diets, was further positively correlated with several amino acid and carbohydrate metabolism pathways, including branched-chain amino acid (BCAA) metabolism.

To investigate the long-term effects of a specific exercise type and athlete diets on the gut microbiota, Jang et al. compared fecal microbiota characteristics, dietary intake, and body composition in 15 healthy sedentary men (as controls), 15 bodybuilders, and 15 long-distance runners. The type of exercise was associated with the athlete's dietary patterns (i.e., bodybuilders: high-protein, high-fat, and low-carbohydrate/dietary fiber diet; long-distance runners: low-carbohydrate and dietary fiber diet). Although athlete type did not differ in terms of gut microbiota alpha and beta diversity, it was significantly associated with the relative abundance of several bacteria. For example, at the genus level, Faecalibacterium, Sutterella, Clostridium, Haemophilus, and Eisenbergiella were highest, while Bifidobacterium and Parasutterella were lowest in bodybuilders. At the species level, beneficial intestinal bacteria widely used as probiotics (Bifidobacterium adolescentis, Bifidobacterium longum, Lactobacillus sakei) and those that produce short-chain fatty acids (Blautia wexlerae, Eubacterium hallii) were lowest in bodybuilders and highest in controls. In long-distance runners, protein intake was negatively correlated with diversity (Shannon index R = -0.63; P = 0.01), and in bodybuilders, fat intake was negatively correlated with Bifidobacteria (R = -0.52; P = 0.05). These differences may be related to the nutritional status of the athletes in the study (i.e., insufficient carbohydrates and dietary fiber; high fat content).

Furthermore, the gut microbiota, with its ability to harvest energy, modulate the immune system, and influence gastrointestinal health, likely plays an important role in athlete health, well-being, and sports performance. Therefore, understanding the mechanisms by which the gut microbiota could influence athletic performance is of considerable interest to athletes working to improve their competitive results, as well as reduce recovery time during training. Ultimately, this research is expected to extend beyond athletics, as understanding optimal physical fitness has applications for general health and well-being in larger communities. Therefore, the objective of this narrative review is to summarize the current knowledge of the athlete's gut microbiota and the factors that shape it. Exercise, associated dietary factors, and athletic classification promote a more “health-associated” gut microbiota. Such characteristics include a greater abundance of health-promoting bacterial species, greater microbial diversity, functional metabolic capacity, and microorganism-associated metabolites, stimulation of bacterial abundance that can modulate mucosal immunity, and improved gastrointestinal barrier function.

• Diet is an established modulator of gut microbiota composition and activity, with marked changes in microbiota composition evident within 24 hours of a dietary change. • Energy balance is currently an overlooked factor regarding the athlete's gut microbiota, particularly in those affected by RED-S ("overtraining syndrome"). • Investigating only the impact of total energy consumption without considering dietary variability is difficult (if not impossible). • The effects of high-protein consumption (without concomitant high-fat) on gut bacteria are not well-studied. This also includes the effects of high-protein and fiber intake. • Protein intake appears to be a strong modulator of microbiota diversity, with protein supplementation, such as whey, showing potential benefits that need further study in humans. • Plant-based proteins have a marked effect on the gut microbiota but currently require investigation in athletes. • In future studies, the types and amounts of fats consumed in conjunction with proteins should be investigated for their overall effect on the gut microbiota. • Increased dietary fiber intake is associated with microbial richness and/or diversity. • Higher carbohydrate and dietary fiber intake in athletes appears to be associated with a greater abundance of Prevotella. • The specific effects of fat on the gut microbiota are difficult to isolate; however, the types of fats consumed appear to be important.

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Clark A, Mach N. Exercise-induced stress behavior, gut-microbiota-brain axis 38. and diet: a systematic review for athletes. J Int Soc Sports Nutr. 2016;13:43 https://doi.org/10.1186/s12970-016-0155-6.

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