Gut microbiota diversity is associated with cardiorespiratory fitness in post-primary treatment breast cancer survivors

Cancer treatment uniquely triggers multiple physiological shifts detrimental to overall health. Although previous research indicates a link between the gut microbiota and cardiorespiratory fitness, it is unclear whether these findings are attributable to potential underlying effects of percentage body fat or free-living activity energy expenditure (AEE). The microbe composition of faecal specimens from 37 breast cancer survivors was determined using 16S microbiome analyses. Individual-sample microbiota diversity (-diversity) and between-sample community differences (-diversity) were examined. Peak oxygen uptake (V.</mml:mover>O2 peak ) was estimated from a graded exercise test consistent with the modified Naughton protocol, in which exercise terminates at 85% of age-predicted maximal heart rate. The AEE was measured over 10days using doubly labelled water, wherein the percentage body fat was calculated from total body water. Pearson correlations revealed -diversity indices (Chao1, observed species, PD whole tree and Shannon) to be positively associated with V<mml:mo>.</mml:mover>O2 peak (r=0.34-0.51; P<0.05), whereas the percentage of maximal heart rate during stages1-4 of the graded exercise test (r=-0.34 to -0.50; P<0.05) and percentage body fat (r=-0.32 to -0.41; P<0.05) were negatively associated with the same -diversity indices. Multiple linear regression models showed that <mml:mover accent="true">V<mml:mo>.</mml:mover>O2 peak accounted for 22 and 26% of the variance in taxonomic richness (observed species) and phylogenic diversity after adjustment for percentage body fat and menopausal status. Unweighted UniFrac (-diversity) was significant for several outcomes involving cardiorespiratory fitness, and significant taxa comparisons were found. Associations between gut microbiota and free-living AEE were not found. Results from the present work suggest that cardiorespiratory fitness, not physical activity, is a superior correlate of gut microbiota diversity.