Fit for the gut: Cardiorespiratory fitness boosts gut bacteria diversity, study finds

19 Feb 2019 --- Cardiorespiratory fitness influences the diversity of gut microbiota more than body fat percentage or general physical activity, according to new research published yesterday in Experimental Physiology. The findings of the study suggest that exercising at high-intensity levels may positively alter the presence, activity and clustering of gut microbes which promote health.

Until now, it was unclear how body fat percentage or physical activity related to greater microbiota diversity, despite its link to cardiorespiratory fitness being known. Such exercise-induced improvements, in cardiorespiratory fitness, often correspond with central (increased volume of blood pumped by the heart with each beat) and peripheral adaptations (increased number of capillaries to transport oxygen from the blood to the muscles).

The research was performed on cancer survivors, as cancer treatment triggers physiological changes that negatively affect cardio-metabolic health and cardiorespiratory fitness and increase body fat percentage. The study, therefore, involved 37 non-metastatic breast cancer survivors, who had completed treatment at least one year prior.

The participants underwent a graded exercise test to determine peak cardiorespiratory fitness, assessments of total energy expenditure and examination of gut microbiota from fecal swipes. Those with the higher cardiorespiratory fitness had greater gut microbiota diversity when compared to less fit participants. Additional statistical analysis highlighted that cardiorespiratory fitness accounted for roughly 25 percent of the variance in species richness and evenness, regardless of body fat percentage.

Despite the importance of the findings, the researchers believe that more research is needed as the cross-sectional nature of the study design offered certain limitations. The results are correlative in nature as the participants were all women who had survived breast cancer and the findings can’t liberally be applied to include other groups. 

“Our group is actively pursuing an interventional study to determine how variation in exercise intensity can influence gut microbiota diversity under controlled-feeding conditions to uncover how exercise may affect functional outcomes of gut microbiota, as well as studying how exercise prescription may be optimized to enhance health outcomes among clinical populations,” says Stephen Carter of Indiana University, US, lead author of the paper. 

The gut microbiome is still a fertile ground for scientists, with research continually bringing new information to the fore. Recently, researchers from the European Molecular Biology Laboratory's (EMBL) European Bioinformatics Institute (EBI) and the Wellcome Sanger Institute uncovered 100 previously unknown bacterial species and then moved on to identify roughly 2,000 gut bacteria using a wide range computational methods. 

The findings are mostly based on European and Northern American samples and the researchers have highlighted the need for data from other regions of the world.