When milliseconds can mean the difference between silver and gold, endurance athletes in sports such as marathon running, cycling, rowing and swimming optimize every aspect of their physiology for a competitive advantage.
Many of these efforts result in improved performance of mitochondria, the tiny but powerful powerhouses that generate energy inside your cells. Carefully calibrated doses of exercise combined with beneficial stress – altitude, cold and heat – and optimized recovery in the form of nutrition, meditation and sleep positively affect the number and health of mitochondria in muscle cells, heart and your brain.
But there’s another aspect of endurance training that may have been largely overlooked by athletes and coaches—the role of the gut microbiome in optimizing your mitochondrial health and fitness.
I am a physician-scientist and gastroenterologist who has studied how nutrition affects the role of the gut microbiome in health and disease for over 20 years. While research evaluating the effects of nutrition on the microbiome and mitochondria is improving our understanding of conditions such as obesity, cancer, rheumatoid arthritis and Alzheimer’s disease, it can also help athletes reach new levels of performance through innovative approaches to nutrition.
Of microbiomes and mitochondria
The gut microbiome, a hidden factory of highly cooperative microorganisms in your gut, keeps your metabolism, immune system, and brain running smoothly. Some researchers liken it to another organ that senses nutritional inputs, produces signaling molecules, and prepares your body to respond appropriately.
Research has shown that endurance athletes have different gut microbiomes compared to the general population. The composition and function of their microbiome, such as increased production of a short-chain fatty acid called butyrate, is linked to increased VO.2 max, a fitness benchmark that measures your ability to consume oxygen during intense exercise. One organism in particular, Veillonella found in some elite runners and can help increase lactate threshold, a fitness metric closely related to mitochondrial function and how long an athlete is able to sustain intense effort.
A healthy microbiome communicates with mitochondria, the tiny structures inside your cells that convert calories into the raw cellular energy needed for muscle contraction and other essential functions. It does this by transforming the undigested food components of a healthy diet—such as fiber, unsaturated fats, and polyphenols—into molecules that increase the number and health of your mitochondria.
Some of these metabolites—butyrate, conjugated linoleic acid, and urolithin A among them—have been shown to specifically improve muscle strength and endurance. Combining exercise with diets high in fiber, polyphenols – a chemical compound from plants – and healthy fats can increase mitochondrial capacity and improve exercise performance.
Nutritional mistakes and deficiencies
Healthy diets are critical for microbiome and mitochondrial health. Conversely, ultra-processed diets have been linked to conditions ranging from obesity and cancer to autoimmune diseases and Alzheimer’s disease. Some people believe that athletes are protected from the negative health effects of ultra-processed diets because of the beneficial effects of exercise. While this may be partially true, it is important to consider other factors in the diet beyond just calories burned.
Additives used to improve the taste and appearance of food, such as emulsifiers, can negatively affect the gut microbiome, compromising the gut barrier and causing systemic inflammation, an unhealthy condition associated with metabolic diseases, cancer, autoimmune conditions and neurodegenerative diseases. Ultra-processed foods have also removed key factors like fiber, polyphenols, and healthy fats found in whole foods that support gut health and signal mitochondria that there are calories to metabolize.
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Drinks, shakes, bars and gels used for endurance sports are processed foods formulated to provide concentrated and accessible energy during intense exercise. While unhealthy in other contexts, they can be key to performance enhancement during long endurance events when your body depletes its version of accessible carbohydrates called glycogen.
But it’s important to supplement these energy supplements with a healthy diet in the recovery hours after exercise. Combining an unhealthy basic diet with high-intensity exercise can compromise your gut barrier and increase inflammation. This has been linked to various exercise-related issues, including gastrointestinal upset, musculoskeletal injuries and respiratory illnesses.
Performance-enhancing microbes
Reintroducing a diet rich in foods that positively impact your microbiome—beans, nuts, seeds, whole grains, fruits, and vegetables—during the recovery phase of exercise can help most people prevent the negative effects of high-intensity exercise and optimize performance.
However, due to the misuse of antibiotics and processed diets, some people lack the key microbes and metabolic machinery needed to convert fiber and polyphenols into beneficial molecules that the body can use. This deficiency may explain why some healthy foods and diets may not be beneficial or tolerated by everyone.
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Healthy diets can then benefit from reintroducing key microbes to the gastrointestinal tract. Research has shown that specific strains of probiotic bacteria can improve barrier function, reduce systemic inflammation, and potentially improve athletic performance by mitigating the side effects of high-intensity exercise. An alternative approach is to increase consumption of fermented foods, such as yogurt and pickled vegetables, which may increase microbiome diversity and decrease systemic inflammation.
In some cases, healthy foods can also be supplemented by providing the body with key metabolites that microbes produce. Research shows that these metabolites – also called postbiotics or exercise mimetics – improve muscle strength and exercise performance. Some postbiotics also work as prebiotics that promote the growth of healthy microbes and help restore a damaged microbiome.
From search to podium
While the benefits of nutrition targeting your microbiome and mitochondria for overall health are increasingly clear, this approach is still in the early days of exploration in endurance sports.
For the occasional exerciser and weekend warrior, all nutritional strategies that support the microbiome and mitochondria can be quite beneficial. These strategies have the potential to improve performance, protect against the negative effects of exercise, and prevent chronic health conditions such as obesity, cancer, and Alzheimer’s disease.
For elite athletes looking for even the smallest improvements to an already fine-tuned training regimen, further research into the impact of the gut microbiome on performance could be invaluable. In a highly competitive field where nothing can be left off the table – or in the closet – such interventions may just be the deciding factor between finishing on or off the podium.