Elite athletes’ poop may hold clues to boosting metabolism

One of the keys to performing like an elite athlete — or at least having the metabolism of one — may be pooping like one. Transplanting feces from certain top-level cyclists and soccer players into mice boosted levels of a molecule that fuels intense workouts, researchers report March 27 in Cell Reports.

Our gut microbiota — the collection of bacteria and other microorganisms living in our digestive tract — play a crucial role in helping us digest food. When digestion goes terribly awry, a refresh of these gut bacteria may provide relief. Fecal microbiota transplants, in which a donor’s poop is transplanted into another person’s gut, have been used to treat inflammatory bowel disease and other conditions.

Frédéric Derbré, a physiologist at Rennes 2 University in France, and his colleagues wanted to analyze the gut microbiota of top-level athletes and see how mice fared when they received fecal transplants from these athletes. The team focused on both athletes and nonathletes who maintained healthy diets to rule out gut microbiota differences caused by varying eating habits.  

Analysis of the cohort’s poop revealed that athletes with the highest exercise capacities had less diverse gut microbiota and lower overall amounts of gut bacteria compared to other study participants. Despite that, they also had higher levels of metabolites called short-chain fatty acids, produced by gut bacteria and used as energy sources. Derbré says the bacteria in these athletes’ guts may extract nutrients from food more efficiently — a hypothesis that requires further study.

Mice given fecal transplants from athletes with very high exercise capacity were more sensitive to insulin and had increased stores of a molecule called glycogen, an important energy source, compared to other transplanted mice.

Still, the mice didn’t show increased running endurance, suggesting that more than a fecal transplant is needed to act like an elite athlete.

Nonetheless, the possible metabolic benefits suggest that a person’s exercise capacity should be considered when selecting donors for fecal microbiota transplantation, Derbré says.

“It’s a long-winded way of just showing that being more physically active and having a healthy diet is very good for you,” says Edward Chambers, a physiologist at Imperial College London who was not involved in the research. As for how the treatment might translate to humans, Chambers says that supplementing a diet with short-chain fatty acids might be less invasive and expensive than fecal microbiota transplantation.