How the Gut Microbiome and Mitochondria Could Improve Endurance Performance

For endurance athletes in disciplines such as marathon running, cycling, rowing and swimming, milliseconds can separate silver from gold, so every part of their physiology is refined to gain a competitive advantage.

Many of these interventions seek to boost the performance of mitochondria: the small yet powerful energy-producing structures inside cells.

Precisely planned exercise doses, alongside useful forms of stress such as altitude, cold and heat, and well-managed recovery through nutrition, meditation and sleep, can improve both the quantity and condition of mitochondria in muscle, heart and brain cells.

Yet another element of endurance training may have received too little attention from athletes and coaches: how the gut microbiome could help optimise mitochondrial health and fitness.

I am a physician-scientist and gastroenterologist, and for more than 20 years I have examined how food shapes the gut microbiome’s role in health and disease.

Research into how food influences both the microbiome and mitochondria is strengthening understanding of conditions including obesity, cancer, rheumatoid arthritis and Alzheimer’s disease. It may also enable athletes to reach new performance levels through novel nutritional methods.

Microbiomes, mitochondria and endurance athletes

The gut microbiome is a concealed production centre of intensely cooperative microorganisms in the intestines, helping to keep metabolism, the immune system and the brain functioning effectively.

Some scientists compare it with an additional organ: one that detects nutritional inputs, produces signalling molecules and readies the body to respond in the right way.

Studies have found that endurance athletes possess gut microbiomes that differ from those of the wider population.

Characteristics of their microbiomes, including greater production of the short-chain fatty acid butyrate, are linked with higher VO₂ max. This fitness measure assesses the capacity to use oxygen during strenuous exercise.

One microorganism in particular, Veillonella, occurs in certain elite runners and may increase lactate threshold. This fitness marker is closely connected to mitochondrial function and to the duration for which an athlete can maintain intense exertion.

A healthy microbiome communicates with mitochondria, the minute structures in cells that turn calories into the fundamental cellular energy needed for muscle contractions and other vital processes.

It achieves this by converting undigested elements of a healthy diet - including fibre, polyunsaturated fats and polyphenols - into molecules that boost mitochondrial numbers and health.

Evidence indicates that several such metabolites, including butyrate, conjugated linoleic acid and urolithin A, can specifically enhance muscle strength and endurance.

Pairing exercise with diets rich in fibre, polyphenols - plant-derived chemical compounds - and healthy fats may therefore improve mitochondrial fitness and exercise performance.

Dietary mistakes and nutritional shortfalls

A healthy diet is essential to the health of both the microbiome and mitochondria. In contrast, ultra-processed diets have been associated with illnesses from obesity and cancer to autoimmune disease and Alzheimer’s disease.

Some people argue that exercise protects athletes against the harmful health consequences of ultra-processed diets. Although this may be partly correct, dietary considerations beyond the number of calories burned still matter.

Food additives intended to enhance flavour and appearance, such as emulsifiers, may harm the gut microbiome. They can weaken the gut barrier and trigger systemic inflammation, an unhealthy state associated with metabolic disease, cancer, autoimmune conditions and neurodegenerative diseases.

Ultra-processed foods also lack important components present in whole foods, including fibre, polyphenols and healthy fats. These support gut health and signal to mitochondria that calories are available to metabolise.

Drinks, shakes, bars and gels used in endurance sport are processed products designed to supply concentrated, readily available energy during hard exercise.

Although they would be unhealthy in other settings, these products can be vital for performance in lengthy endurance events, when the body uses up its own readily accessible carbohydrate stores, known as glycogen.

However, these energy supplements should be accompanied by a healthy diet during the recovery period after exercise.

A poor baseline diet combined with high-intensity exercise may damage the gut barrier and raise inflammation. This combination has been linked with several training-related problems, including gastrointestinal distress, musculoskeletal injuries and respiratory illnesses.

Microbes that may enhance performance

For most people, restoring foods that benefit the microbiome during training recovery - beans, nuts, seeds, whole grains, fruit and vegetables - can reduce the harmful effects of high-intensity exercise and support better performance.

However, antibiotic misuse and processed diets mean that some people are missing the important microbes and metabolic machinery required to transform fibres and polyphenols into beneficial molecules the body can use. This deficiency may help explain why certain healthy foods and diets are not beneficial or well tolerated by everyone.

Healthy diets may therefore benefit from putting key microbes back into the gastrointestinal tract.

Research indicates that particular strains of probiotic bacteria can strengthen barrier function, lower systemic inflammation and potentially improve athletic performance by reducing the side effects of high-intensity exercise.

Another option is to eat more fermented foods, including yoghurt and pickled vegetables, which may increase microbiome diversity while reducing systemic inflammation.

In some situations, healthy foods could also be supported by directly supplying the body with the vital metabolites made by microbes. Studies show that these metabolites, known as postbiotics or exercise mimetics, improve muscle strength and exercise performance.

Certain postbiotics also act as prebiotics, feeding the growth of beneficial microbes and helping to repair a damaged microbiome.

From laboratory findings to the podium

Although the general-health advantages of nutrition that targets the microbiome and mitochondria are becoming clearer, its use in endurance sport remains at an early stage of investigation.

For occasional exercisers and weekend warriors, broad nutritional approaches that support the microbiome and mitochondria may be particularly useful. They could improve performance, guard against harmful training effects and help prevent chronic conditions such as obesity, cancer and Alzheimer’s disease.

For elite athletes pursuing even the smallest gains within an already carefully refined training programme, further research into the gut microbiome’s effect on performance could prove invaluable.

In an intensely competitive arena where nothing can be overlooked - whether on the table or in the cupboard - these interventions could be what determines whether an athlete reaches the podium or misses it.

Christopher Damman, Associate Professor of Gastroenterology, School of Medicine, University of Washington

This article is republished from The Conversation under a Creative Commons licence. Read the original article.