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Athletes' Gut Microbiomes Include Bacteria That May Boost Performance

NEW YORK (GenomeWeb) – The gut microbiomes of athletes harbor bacteria that may aid their performance, a new study has found.

Researchers from Harvard Medical School collected fecal samples from individuals who ran the Boston Marathon and from sedentary individuals and found differences in the prevalence of bacteria belonging to the genus Veillonella. As they reported in Nature Medicine today, these bacteria metabolize lactic acid, turning it into propionate, which then boosts exercise capacity.

"The microbiome is such a powerful metabolic engine," senior author Aleksandar Kostic, a researcher at the Joslin Diabetes Center and at Harvard Medical School, said in a statement. "This is one of the first studies to directly show a strong example of symbiosis between microbes and their human host."

"It's very clear. It creates this positive feedback loop," he added.

To build on previous studies that had found elevated levels of certain bacteria among the gut microbiomes of athletes, the researchers collected a total of 209 fecal samples from 15 individuals who ran the 2015 Boston Marathon and from 10 sedentary controls, starting a week before and ending a week after the race. Based on 16S ribsosomal DNA sequencing, the researchers found Veillonella to be more abundant among the runners than the non-runners. In addition,  Veillonella numbers were higher among the runners after the race than before the race.

In a follow-up mouse experiment aimed at examining whether Veillonella contributed to the marathoners' performance, the researchers fed mice either a Veillonella atypica strain, isolated from one of the runners, or Lactobacillus bulgaricus, which, unlike Veillonella, does not influence lactate metabolism. After inoculation, the mice ran on a treadmill until exhaustion.

Mice given V. atypica were able to run an average 13 percent longer than the control-treated mice, the researchers reported.

They then replicated their findings using stool samples from a cohort of ultramarathoners and Olympic trial rowers before and after exercising. Shotgun metagenomic sequencing of these samples further revealed a group of gene families whose relative abundance changed before and after exercise. These genes encompassed each step of the enriched methylmalonyl-CoA pathway, which degrades lactate into propionate.

This, they said, could mean that Veillonella alters the metabolic capabilities of the human gut microbiome. Through mass spectrometry analysis, they confirmed high acetate and propionate levels after growing Veillonella strains isolated from athletes on two types of media.

This suggested to the researchers that not only is Veillonella enriched after exercise in these athletes, but so is the metabolic pathway it uses to metabolize lactate.

In another set of mouse studies, the researchers injected mice colonized with either V. atypica or L. bulgaricus with 13C3 sodium lactate and, using LC-MS, found 13C3-labeled lactate in their serum and plasma, as well as in the lumen of the colon and ceca, suggesting serum lactate can enter the intestinal lumen.

They also introduced propionate or saline intrarectally into a cohort of mice to find that, after treatment, mice given propionate had increased treadmill run times, in line with those of Veillonella-treated mice.

Together, this suggested to the researchers that systemic lactate produced during exercise could cross into the gut where Veillonella metabolizes it into propionate, which then promotes performance. They plan to next investigate the mechanism of just how propionate affects exercise capacity.

"Having increased exercise capacity is a strong predictor of overall health and protection against cardiovascular disease, diabetes, and overall longevity," Kostic said. "What we envision is a probiotic supplement that people can take that will increase their ability to do meaningful exercise and therefore protect them against chronic diseases including diabetes."

Study authors Jonathan Scheiman and George Church, both researchers at Harvard Medical School, are also cofounders of FitBiomics, a microbiome-based biotech firm that plans to develop novel probiotics to aid athletic performance and recovery. Kostic also holds equity in FitBiomics.