The modification of the human gut microbiota’s composition and function is one of the plausible mechanisms that has just recently started being explored in relation to how exercise affects health. Although gut microbiome composition tends to show higher variability under environmental pressures, its diversity functionality tends to remain consistent within and across subjects. In professional athletes, however, little is known about how microbial metabolism is related to performance.
A new study, led by Dr. Aleksandar D. Kostic from Harvard Medical School (USA), and whose lead author is Jonathan Scheiman—one of the founders of the start-up Fitbiomics, which is looking to find new probiotic candidates for promoting wellness—provides the first example of evidence that the metabolism of lactate to propionate may enhance athletic performance in mice.
Initially, researchers compared bacterial strains present in stool samples from two independent cohorts—15 runners and 87 ultramarathoners and Olympic trial rowers—both before and after exercise. After the endurance competition, an increase was identified in Veillonella relative abundance and especially in Veillonella atypica, of which an increased presence had previously been found in the athlete microbiome. This bacterium also appeared to be more abundant in athletes compared with 10 non-athletes.
Microbial genes for lactate-to-propionate conversion via the methylmalonyl-CoA pathway were also increased in athletes.
The researchers later explored whether Veillonella or propionate might be responsible for an improvement in athletic performance in mice.
Both oral Veillonella administration and rectal administration of propionate increased treadmill running times in mice, with performance gains related to propionate production rather than lactate clearance. In addition, the investigators established that serum lactate can cross the epithelial barrier into the gut lumen, where Veillonella converts it into short chain fatty acids (mainly propionate, but also acetate).
From the biochemistry point of view, these findings are like a prolongation of the Cori cycle that, in this case, allows the lactate exercise by-product to be converted into propionate through the athlete gut microbiome.
On the whole, these findings show the first evidence in a mouse model of the microbial modulation of athletic performance. And as science writer Emily Willingham explains in this Scientific American article, the results of this study captured the attention of anti-doping agencies. In the light of these preliminary findings in mice, however, the extent to which gut microbiota-derived metabolites such as propionate should be included in the prohibited list of substances with performance-enhancing effects remains unknown.
Scheiman J, Luber JM, Chavkin TA, et al. Meta-omics analysis of elite athletes identifies a performance-enhancing microbe that functions via lactate metabolism. Nat Med. 2019. doi: 10.1038/s41591-019-0485-4.
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