The Harvard researchers sampled the gut microbiomes of athletes training for the Boston Marathon. After the marathon, the runners showed a spike in one type of bacteria.The researchers later did a second analysis of 87 ultra-marathoners and Olympic-trial rowers and found similarly high levels of Veillonella. In addition, when comparing the gut microbiomes of rowers and ultramarathoners. They found differences in composition, which suggests that certain sports might foster certain microbial ecosystems.
Digging deeper It appears that Veillonella thrived by feeding off lactic acid, a compound produced in the muscles during exercise. Lactate is produced in the muscles and travels through the bloodstream to the liver, where it is converted into glucose to fuel exercise.
The bacteria then turns the lactic acid into a compound called propionate (a common short-chain fatty acid), which may aid in boosting one’s athletic performance. Though a few groups of bacteria in the gut are able to eat lactate, Veillonella is one of the only groups that can convert lactate into short-chain fatty acids. Short-chain fatty acids are typically a hallmark of healthy guts as they have a number of beneficial properties including fighting inflammation and serving as an energy source for cells. .
This connection between Veillonella, lactate, and exercise prompted the researchers to wonder whether giving Veillonella to mice might affect their endurance.
So they performed a series of further experiments to investigate.
First they isolated a sample of the species Veillonella atypica from one of the marathon runners and administered it to 16 mice. Then they gave Lactobacillus bulgaricus, another bacterium that does not eat lactate to another 16 mice. Then they had all the mice run on a treadmill until exhaustion.
Sure enough, the mice given Veillonella ran 13% longer than the mice given the microbe that could not eat lactate. But the researchers wondered how the lactate made its way into the gut, where the Veillonella bacteria were waiting to break it down.
To find out, they tagged lactate molecules with a radioactive marker and injected them into the tails of four mice. They found that a portion of the labeled lactate molecules moved from the bloodstream into the liver as expected, but a portion also traveled directly into the gut.
This finding prompted the researchers to wonder whether they could boost the endurance of mice introducing propionate directly into their colons via a standard enema.
And it did!
The mice given propionate directly ran just as long as the mice that were given Veillonella. The researchers saw this as an indication that the propionate produced by Veillonella, not the Veillonella itself, was allowing the mice to run for a longer time.
This discovery was a “lightbulb” moment for the researchers because lactate is a metabolite that accumulates in the blood after strenuous exercise. And, when your ability to utilize lactate gets outpaced by your ability to produce it, lactic acid starts to accumulate in the blood causing fatigue.
In short, the researchers feel that someday we may be able to take Veillonella or other bacteria just before we exercise so we can go harder, longer and faster.