After the excesses of the holiday season, many people make a New Year’s resolution to take better care of themselves, and that might be achieved by following a more balanced and healthy diet and returning to or taking up exercise. The gut microbiota can be a great ally in ensuring people get the maximum benefit from such changes in habit, says nutritionist and biologist Daniel Badia, who specializes in food and sport and is a professor at the Open University of Catalonia, Spain.

“The gut microbiota influences our overall health and well-being,” says Badia. “And in the case of athletes—not just elite sportspeople but anyone who does exercise—it also conditions their performance.”

According to the nutritionist, an unbalanced diet can cause intestinal discomfort, such as abdominal distension, nutritional deficiencies, excessive fermentations, intestinal permeability and even a sense of increased fatigue after exercising.

Following a healthy and balanced diet, meanwhile, promotes a healthy microbiota that could influence athletic performance

“We see the benefits of a balanced microbiota when we no longer have them,” he points out and adds that “an unbalanced microbiota contributes to global inflammation of the body, which affects muscle recovery capacity.”

Following a healthy and balanced diet, meanwhile, promotes a healthy microbiota that could influence athletic performance. The key is the process of fermentation by bacteria of certain fiber-rich foods in the large intestine and the subsequent production of short-chain fatty acids (SCFAs). Those SCFAs, Badia says, can be oxidized in muscle, which contributes to making muscle glucose more available. They also promote increased blood flow, insulin sensitivity and muscle mass preservation, which are all key aspects, from both an overall health and performance point of view.

“Specifically, it has been observed that the bacterial species that produce a type of SCFA, called butyrate, have the greatest positive effect on both performance and muscle recovery,” says the expert, highlighting that few studies corroborate this. “The maximum volume of oxygen that an athlete is capable of using—a measure of direct performance at a metabolic level—has been analyzed and it has been observed that higher levels of butyrate production have an impact on an increased capacity for using oxygen,” says Badia.

One of the best known and most revealing studies on the influence of the intestinal microbiota on sports performance, carried out during the Boston Marathon in 2014 by researchers from Harvard Medical School, pointed out the importance of butyrate. In a study published in Nature, scientists explained that marathon participants who were in better shape had higher levels of the SCFA in their stool. And butyrate is also one of the main sources of energy for the cells that line the intestinal epithelium, so generating more of it when exercising also had an impact on better gastrointestinal health.

Among all the butyrate-producing bacteria, the Harvard researchers observed that, after the marathon, runners had a higher abundance of Veillonella in their feces. The team then managed to replicate the results in an independent cohort of rowers and elite runners.

According to scientists, Veillonella is responsible for metabolizing lactate, which is a molecule that produces anaerobic respiration and is responsible for the pain caused by stiffness following intense exercise. Lactate is generated in abundance in a marathon and Veillonella uses it to generate energy. In return, Veillonella produces butyrate, which promotes muscle function and thus closes a virtuous circle. Indeed, when mice were given a Veillonella-based probiotic in a subsequent experiment, the animals ran for 13% longer.

The Nature study is not the only one to have found a link between sports performance and microbiota. It has also been shown that regular moderate exercise increases microbial diversity, which results in better physical and mental health through, for example, the functioning of the metabolism and the body’s immune response. As for the type of training, we can state that both exercise intensity and duration impact the human gut microbiota. Endurance exercises such as athletics can have adverse effects on the gut microbiota (e.g., increased intestinal permeability and negative changes in the composition of gut microbiota) and strength training offers minimum benefits. In contrast, aerobic exercise seems the most beneficial for the gut microbiota.

“It’s enough to do moderate exercise four or five days a week, such as walking quickly, climbing stairs, and doing some training activity, such as swimming or cycling, to get the benefit,” says Badia.

Of course, the key is moderation. Recent work on the effect of sports practice on the microbiota suggests that workouts that are irregular, very strenuous and long can cause imbalances in the composition of gut bacteria. And that, in turn, has been seen to influence immune response and can lead to health problems in athletes, such as gastrointestinal and respiratory infections.

Moreover, you don’t have to be an elite athlete to enjoy the benefits of physical activity. “It’s enough to do moderate exercise four or five days a week, such as walking quickly, climbing stairs, and doing some training activity, such as swimming or cycling, to get the benefit,” says Badia.

Of course, he emphasizes that it is crucial to follow a diet that contains all the products that are known to improve the quantity, variety and activity of the bacteria that live in the gut. “If we want to have a healthy and diverse microbiota, we have to feed all microbial species, and that means following a diet with an abundance of plant foods, which are as varied as possible.”

That variety of vegetables, fruit, nuts, whole grains and legumes, all rich in fermentable fiber and prebiotics, is important. In addition to fiber, the microbiota also benefits from the polyphenols present in curcumin, the resveratrol of grapes and the epigallocatechins of green tea. And the same can be said for healthy fats, such as extra virgin olive oil, and quality proteins, such as organic eggs, legumes and organic grass-fed meat.

Consuming fermented products and probiotics, such as fermented milks (yogurt, kefir), sauerkraut, miso soup or unpasteurized olives, is also a good way to take care of the gut microbiota.




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