Athletes, particularly those at the top of their profession appear to be are big winners when it comes to their gut microflora. A recent paper suggests that exercise has a direct effect on microbial composition and related gastrointestinal health. The article ‘Exercise and associated dietary extremes impact on gut microbial diversity’ was published in the international journal GUT.[1]

The relationship among the gut microbiota, exercise and related dietary changes has received much less attention. Loss of community richness/biodiversity has been demonstrated in obesity studies while increased diversity, which has been advocated to promote stability and improved ecosystem performance, is associated with increased health in certain populations. This has led to the suggestion that microbiota diversity could become a new biomarker for health status. It has been suggested that monitoring the gut microbiota annually to determine changes in the composition and stability could be sufficient to detect health status changes.

This article is the first report that exercise increases gut microbiota richness/diversity and highlights that exercise is another important factor in the complex relationship among the host, host immunity and the microbiota.

In this paper, DNA sequencing of faecal samples from players in an international rugby union team showed considerably greater diversity of gut bacteria than samples from people who are more sedentary.

The authors state:

“Our findings show that a combination of exercise and diet impacts on gut microbial diversity. In particular, the enhanced diversity of the microbiota correlates with exercise and dietary protein consumption in the athlete group,” the authors write.

The investigators used 16S ribosomal RNA amplicon sequencing to evaluate stool and blood samples from 40 male elite professional rugby players (mean age, 29 years) and 46 healthy age-matched control participants. The researchers evenly divided control participants between those with a low body mass index (BMI), defined as a BMI of 25 kg/m2 or less, and those with a high BMI (>28 kg/m2). Participants also filled out food and exercise questionnaires.

Relative to control participants with a high BMI, athletes and control participants with a low BMI had improved metabolic markers. In addition, although athletes had significantly increased levels of creatine kinase, they also had overall lower levels of inflammatory markers than either of the control groups.

Athletes were also found to have more diverse gut microbiota than controls, with organisms in approximately 22 different phyla, 68 families, and 113 genera. Participants with a low BMI were colonized by organisms in just 11 phyla, 33 families, and 65 genera, and participants with a high BMI had even fewer organisms in only 9 phyla, 33 families, and 61 genera.

The professional rugby players, as the investigators expected, had significantly higher levels of total energy intake than the control participants, with protein accounting for 22% of their total intake compared with 16% for control participants with a low BMI and 15% for control participants with a high BMI.

When the authors looked for correlations between health parameters and diet with various microbes or microbial diversity, they found significant positive association between microbial diversity and protein intake, creatine kinase levels, and urea.


“The fact remains though that our gut microbiota is not programmed to keep pace with the demands that modern life throws at us. Research focused on sustaining health rather than restoring health is urgently needed. Understanding the impact of exercise and the nutritional value of foods in terms of relevance to our microbiota is essential,”



[1] Clarke S, Murphy E, O’Sullivan O, et al. Exercise and associated dietary extremes impact on gut microbial diversity. Gut 2014. View Abstract

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