Elite Runners' Gut Microbe Makes Mice More Athletic — Could It Help The Rest Of Us?

Competitive runners (myself included, once upon a time) will try almost anything that could give them a natural edge in their next 5K or 10K.

Down concentrated beet juice before a race? I've done it.

Eat chia seeds by the handful? Yep.

Altitude tents that mimic life at 10,000 feet? If only I had the money.

But new research hints that, perhaps, someday I may add consuming bacteria to that list.

A new study out Monday in the journal Nature Medicine identified a group of bacteria that are more common in athletes, especially after exercise, and may play a role in enhancing athletic performance. The researchers isolated this bacterial strain from elite runners, put it into the colons of lab mice and found that these human-derived bacteria boosted the mouse's performance on a treadmill exertion test by 13%.

"This is a really impressive study," says Morgan Langille, a microbiome researcher at Dalhousie University in Nova Scotia who was not involved in the research. "It's the first study I'm aware of that goes beyond correlation to show that certain microbes that increase with exercise actually have an effect [on performance]."

Scientists already knew that exercise subtly changes the makeup of our microbiome. Certain strains flourish in the post-workout gut. But scientists hadn't demonstrated whether any of these exercise-loving microbes actually affect our health or performance.

"If we could identify microbes that do contribute to the health and performance of super healthy people, then maybe we could develop a probiotic to help everyday people perform better," says Jonathan Scheiman, currently the co-founder and CEO of FitBiomics, who led this study while he was a postdoctoral researcher at Harvard Medical School.

For the research, Scheiman would need a good data set of the gut microbes of athletes. So he solicited Boston Marathon runners for their poop.

"A good two weeks of my life was spent driving around Boston in a Zipcar collecting fecal samples from runners," Scheiman says. He wanted to compare their microbes before and after running the marathon, and weigh them against the microbiomes of non-runners.

Scheiman handed off the stool samples to his colleague Aleksandar Kostic, a microbiologist at the Harvard Medical School-affiliated Joslin Diabetes Center (Kostic is also a co-founder and science adviser for FitBiomics). Kostic sequenced the bacterial DNA in the stool samples and looked for differences — either in the kinds of bacteria present or their relative numbers — between the groups.

The differences were subtle. "It's not as though that the microbiome of runners looks completely different from nonrunners," he says. "But one group of bacteria stood out in runners. Veillonella."

Veillonella bacteria seemed to be a bit more common in runners than nonrunners, and it became much more common in the guts of runners after they'd run the marathon.

"We were intrigued, but I didn't know anything about Veillonella," says Scheiman. "So I Googled it."

He learned that Veillonella has a fairly unusual way of making a living — it eats lactate, a chemical byproduct of intense exercise that's associated with fatigue (though, contrary to popular belief, it doesn't actually cause your muscles to hurt).

Scheiman's intrigue grew. "Isn't it interesting that after running a race you have an increase in a kind of bacteria that eats a metabolic byproduct of running a race? ... That was a big lightbulb moment," he says.

At this point, all the researchers had was an interesting correlation. It was a good start, but not enough according to Kostic: "We wanted to understand exactly what Veillonella is doing." Specifically, the researchers wondered if the bacteria might be boosting endurance performance.

So they did an experiment.

Scheiman isolated Veillonella from the stool of one of the marathoners and transferred it into the guts of normal laboratory mice. As a control, he inoculated another group of mice with a different strain of non-lactate eating bacteria.

Then, the two groups faced off in a series of races to exhaustion run on a mouse treadmill.

The Veillonella-treated mice won. On average, they lasted 13% longer (~18 minutes vs. ~16 minutes across all trials) than the control mice.

"We were pretty surprised to see that big of an effect from a [human-derived] bacteria," Scheiman says. "Imagine telling a marathon runner that you could improve their performance by 13%. It'd be huge."

Of course, a 13% boost in one measure of performance in mice does not directly apply to humans. But the researchers wanted to know how bacteria living in the gut (not in muscles or lungs, tissues directly involved in exercise) improved performance in mice so significantly.

The research team thought it might have something to do with how Veillonella breaks down lactate.

Our liver processes excess lactate by converting it to glucose, but Veillonella does something different. It gobbles up lactate and converts it into a molecule called propionate, a short-chain fatty acid that's been shown to affect heart rate and oxygen absorption in mice.

With this in mind, the researchers transferred pure propionate to the guts of mice and ran the same treadmill test. "Lo and behold, propionate produced the same endurance boost as Veillonella," Scheiman says. The researchers found the mechanism. Veillonella enhances the performance of its host by converting lactate to propionate.

But why the bacteria do this is a harder question to answer.

"Athletes that exercise often may simply be creating a gut with higher levels of lactate that allow Veillonella to flourish," Scheiman says. Veillonella might even be pumping out propionate in order to boost the performance of its host in a symbiotic tit-for-tat, according to Scheiman, though that's far from clear. Either way, Scheiman is hoping athletes may some day be able to benefit from its relationship with our guts.

Since conducting this research, he left academia to run the company FitBiomics. "Our mission is to mine the biology of the most fit and healthy people in the world and then aim to translate that data into ... next-generation probiotics," he says. He hopes to start testing Veillonella in human subjects with the ultimate goal of creating an endurance-boosting probiotic.

Langille is a bit more skeptical that someday soon you'll be able to pop Veillonella pill to get a fitness boost. "This research certainly opens the door to that possibility, but often it's harder to replicate an effect you see in mice in human studies," he says.

Langille also suggests that since Veillonella already seems to be more common in athletes, further supplementation may not translate into better performance.

Additionally, while scientists agree there is some evidence that certain probiotics can help people with digestive problems like irritable bowel syndrome, many scientists argue that there's not yet convincing evidence that they help healthy people.

"Still, before this study I don't think anyone would've said that the microbiome could boost athletic performance," Langille says. "It's an intriguing concept."

Jonathan Lambert is a freelance science journalist based in Washington, D.C. You can follow him on Twitter: @evolambert

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