Published by NEJM Journal Watch General Medicine on August 6, 2019
By Anthony L. Komaroff, MD
Marathoners had higher gut concentrations of Veillonella atypica than did nonathletes.
Gut microbes (the microbiome) produce many molecules that affect human physiology. To determine how the microbiome might affect athletic performance, investigators obtained daily stool samples from 15 runners for 1 week before and 1 week after the Boston Marathon and compared the microbiome findings to those of a group of 10 sedentary controls. They then confirmed their findings in a second group of athletes and controls.
Athletes had a higher abundance of one bacterial species, Veillonella atypica, than controls. This species was even more abundant following exercise; in addition, the bacterial genes that convert lactate to propionate were activated by exercise. The researchers then fed V. atypica (isolated from the athletes) to mice. Mice that were fed V. atypica were able to exercise longer than mice fed a lactobacillus control. Blood lactate generated by exercise spilled into the gut lumen, where it was metabolized to propionate by V. atypica; it then was reabsorbed in the colon and entered the circulation. Mice given an intrarectal instillation of propionate also could exercise longer — indicating that additional propionate (not just less lactate) might contribute to better exercise capacity.
This study of human athletes, combined with mouse studies to understand physiologic mechanisms, indicates that at least one bacterial species in the gut might enhance athletic performance by promoting conversion of the lactate produced during exercise into propionate. With this study design, the researchers could not address an obvious question: Does their native microbiome make top marathoners better athletes, or does a marathon training program change the microbiome in a beneficial way — or both? The study suggests another question, as well: Will elite athletes someday be screened not only for performance-enhancing drugs but also for performance-enhancing gut bacteria?