Survival of the Fittest: Athletes' Gut Microbes Are Tailored to Help Them Compete

The bacteria in our gut — a community called the gut microbiome — have been in the spotlight a lot lately. What we're learning about how our intestinal bacteria adapt and grow with our bodies could help athletes perform better, according to researchers starting a company focused on creating probiotics that mimic athletes' microbiomes.

"The bugs in our gut affect our energy metabolism, making it easier to break down carbohydrates, protein, and fiber," researcher Jonathan Scheiman said in a press release from the American Chemical Society. "They are also involved in inflammation and neurological function. So perhaps the microbiome could be relevant for applications in endurance, recovery, and maybe even mental toughness."

Scheiman, a college athlete turned research scientist, and his colleagues conducted the study by following athletes through their stool samples. His work showed that gut bacteria can change in response to the type of exercise done and can change within an individual as the result of strenuous exercise.

The study found that individual marathoners have different bacteria in their guts pre- and post-race. The study also found that ultramarathoners have different gut bacteria than rowers. The work was presented August 20 at the 254th National Meeting & Exposition of the American Chemical Society.

Gut Microbiome & Probiotics

There are at least as many bacterial cells in our gut as all the other cells in our body, and in some people, gut bacteria probably outnumber the 100 trillion human cells in the body two to one.

Research has tied the types and amount of bacteria in our guts to diet, age, and diseases, like diabetes and rheumatoid arthritis. The types and amounts of gut bacteria change with infections like diarrhea-causing Clostridium difficile, as well as medication and antibiotic use. They also play roles in our health, development, endurance, recovery, and mental aptitude.

Some studies have attempted to characterize a typical gut microbiome. Because of all the factors that influence the bacteria there, it's been hard to generalize, but the gut microbiome of people who eat typical American diets contains an abundance of bacteria from the phyla Firmicutes, like lactobacillus, and Bacteroidetes, followed by fewer bacteria from the phyla Actinobacteria and Verrucomicrobia. These bacteria were found in people without disease and felt to represent a healthy gut microbiome.

To keep their guts populated with good types of bacteria, many people turn to probiotics.Probiotics are live good gut bacteria intended to benefit our health. Multitudes of foods, like yogurt, and nutritional supplements contain active bacteria and claim to be probiotic. But, true probiotics have their own set of criteria that establishes them as beneficial. According to a review of scientific publications on probiotics, for bacteria to qualify as probiotics, they must:

1. Be viable during processing, transport, and storage;
2. have the ability to survive gastric transport;
3. have the ability to adhere and colonize the GI tract;
4. have the ability to antagonize pathogenic bacteria; and
5. have demonstrated clinical health outcomes.

With so many different health and environmental influences causing or associated with changes in the gut microbiome, it's no wonder that an elite athlete's gut microbiome is different, too. Scheiman's research compared athletes participating in different sports to each other, and also analyzed the rapid changes in an athlete's gut microbiome before and after a big event.

An Athlete's Gut — They Aren't All Alike

An athlete at heart, Scheiman has never stopped trying to incorporate that love into his work as a research scientist at Harvard.

In an interview with Huffington Post, he described his goals simply: "Recruit elite athletes, sequence athlete microbiome, identify candidate probiotics, isolate novel beneficial strains and add to food."

He was looking for changes in gut bacteria present in marathon runners before and after a race and comparing gut bacteria in two very different types of athletes: ultramarathoners — those who run 100 miles at a time — and Olympic rowers.

Scheiman and his team collected fecal samples daily from 20 athletes training for the 2015 Boston marathon, one week before and one week after the race, to compare pre-and post-race gut bacteria in the runners. They identified a type of bacteria enriched in the gut microbiome after the athletes completed the marathon.

Scheiman isn't ready to name the bacteria yet — he has plans for marketing it as a probiotic supplement —but does say that the bacteria is known to metabolize lactic acid, which builds up in muscles cells in high amounts during strenuous muscular exercise. He hopes the probiotic supplements his company creates will help athletes recover faster from exercise and convert nutrients to energy more efficiently.

In another set of experiments, the researchers compared the gut bacteria from ultramarathoners to those found in rowers training for the Olympics. They found a type of bacteria in ultramarathoners that wasn't present in the rowers. The bacteria were inhabiting their guts before they were even racing, suggesting the rigors of training helped the bacterial populations develop in the athletes. Again, Scheiman isn't ready to divulge the name of the bacteria but says that its function is to help break down carbohydrates and fiber, a key need in a 100-mile race.

Scheiman says his findings show that different microbiomes may develop in athletes in different sports niches and he plans to expand the number and types of athletic microbiomes he studies.

"We're trying to understand what makes these elite athletes unique from a molecular standpoint, then extract that information and provide it to others to benefit and promote general health and well-being, not only in athletes but maybe one day in the general population," said Scheiman.

Previous research has already found that the composition of an athlete's gut microbiome differs from sedentary people. One study of rugby players found their gut microbiome was enriched in a bacteria called Akkermansia muciniphila and had lower numbers of Prevotella. Another study found that gut microbiomes of 33 cyclists either showed high Prevotella, high Bacteroides, or a mix of many bacteria including Bacteroides, Prevotella, Eubacterium, Ruminococcus, and Akkermansia, compared to non-cyclists.

Lynne McFarland Associate Professor at the University of Washington who wasn't associated with the research, urges caution in leaping from an exploratory study of professional athletes to the development of probiotics that can change athletic performance. More research needs to be done to show that the observed reduction in lactic acid levels resulted in better performance, and to compare the athlete's gut bacteria to those of non-athletes in a similar situation, she told Invisiverse.

There's a lot of testing ahead for Scheiman and his team, McFarland warned, "health benefits are found only after two randomized, controlled trials are done because shifts in bacteria and response to 'new medications' are often seen in subjects given placebo."

Scheiman and his team plan to launch a company called Fitbiomics in the fall, and he thinks he may have probiotics ready to market about a year after that. Until then, they'll be doing more research to see if a change in gut bacteria can turn us into better athletes, or at least help us recover better from a tough workout.

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