Lauren Petersen, a scientist at The Jackson Laboratory for Genomic Medicine in Farmington, Connecticut, is one of an elite group of scientists looking at the gut microbiology of athletes. Petersen, who founded the Athlete Microbiome Project, is specifically researching cyclists.

Her connection to the topic is intimate. Petersen contracted Lyme Disease at 11 years old. She was on and off antibiotics and generally sick for more than a decade. Then, as she was finishing her PhD, she gave herself a fecal transplant from a competitive cyclist.

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“I couldn’t find a doctor who could help me,” remembers Petersen. An interest in finding her own solutions had already propelled her towards a career in science, and while she was in grad school she had her gut sequenced by the American Gut Project*. The results showed that her gut microbiome is 96% gram-negative bacteria. While American Gut is purely a research project and results cannot be used as a diagnostic or to inform treatment, Petersen worried that some of these bacteria might be pathogenic, and could get into her blood stream. “I had no microbes to help me break down food, and I had picked up bugs in the lab where I was working because my system was so weak and susceptible.”

But a few months after her transplant, Petersen was training five days a week (up from her usual two). She started enduro racing, and was soon placing and even winning in the pro field. “I wondered if I had gotten my microbiome from a couch potato, not a racer, if I would I be doing so well,” remembers Petersen. "Then it made me wonder what the best possible microbiome for a racer would be.”

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So, she started gathering stool samples from amateur and professional bike racers. She observed that Prevotella, a microorganism she received in her own transplant, is common amongst elite racers. “The more a person trains, the more likely they are to have Prevotella,” says Petersen. “In my sampling, only half of cyclists have Prevotella, but top racers always have it... it’s not even in 10% of non-athletes.”

She is currently extracting Prevotella to understand what it is, and how to boost its abundance naturally or through a probiotic pill for athletes or aspiring athletes. What she already knows: Prevotella synthesize branch chain amino acids critical for muscle recovery.

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In addition to Prevotella, Petersen has identified an archeon named Methanobrevibacter smithii, or M. smithii, which she believes is also significant. Archeon are ancient microorganisms that have managed to survive for millions of years in hostile habitats like sulfur springs and deep in the ocean. They also live in the human digestive system, where they have specialized functions. Like Prevotella, Elite cyclists often have M. smithii, but it’s less common in amateur racers. That’s significant because M. smithii also appears to be a performance-enhancing microbe.

What does it do? In science terms, it thrives on hydrogen and carbon dioxide and other bacterial waste products in the gut. In 12-year old boy terms, M. smithii eats the poop of bacteria. Yes, everybody poops, even bacteria, and it can have detrimental effects on your health. Namely: buildups of hydrogen and carbon dioxide can prevent the other bacteria in your gut from properly breaking down your food for fuel, which is bad news if you need calories for that sprint.

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So in 12-year-old boy terms, M. smithii is kind of like a bacterial pooper scooper. In science terms, it helps you turn the food you’re eating into energy more efficiently. For example, it boosts the ability of your gut bacteria to break down fiber from fruit into the short-chain fatty acids that are critical fuel for athletes.

Petersen is still investigating how different foods can impact Prevotella, M. smithii, and the rest of the 120 species and 350 strains of microbes she’s identified in bike racers' guts. And she doesn’t know if those microorganisms need other ingredients to work. She also doesn’t know if Prevotella and M. smithii are differentiators for cyclists only, or also common in elite basketball players or gymnasts. So unfortunately it could be years, not months, before you’ll be able to buy performance-enhancing probiotics. (In the mean time, you can try top-rated Ultimate Flora for $29 on Amazon.)

As for actual poop doping…. fecal transplants are available, but not in the U.S. And if you do find a clinic willing to do it, Petersen warns that "you can’t choose your donor, and it’s a risky procedure. As with any transplant, your immune system could reject what you get. It’s not something you should take lightly. I did a lot of research, and I took a risk for sure.” To be clear, Petersen  in no way supports 'at home' fecal transplants— she simply thinks there's room to improve our probiotic and prebiotic knowledge. 

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With the data collected from the Athlete Microbiome Project, Petersen is diving into research not just on performance enhancing probiotics for cyclists, but whether cyclist-derived gut microorganisms could boost the health of athletes and non-athletes alike, providing greater long-term benefits than the probiotics currently available.

“What we’re learning is going to change a lot for cyclists as well as the rest of the population,” says Petersen. “If you get tested and you’re missing something, maybe in three years you’ll be able to get it through a pill instead of a fecal transplant. We’ve got data that no one has ever seen before, and we’re learning a lot. And I think I can say with confidence that bacterial doping— call it poop doping, if you must— is coming soon.”

Want to get involved? If you’re a Pro or Cat 1 cyclist and want to share what’s in your gut, contact Lauren

*The American Gut Project does not provide information that should be used for clinical decisions.