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

Abstract

Previous studies have not adequately considered the influence of adiposity and activity-related energy expenditure (AEE) on gut microbe diversity. We determined associations of gut microbiota diversity with measures of cardiorespiratory fitness while accounting for the potential effects of %body fat and free-living AEE. Cancer treatment uniquely triggers multiple physiologic shifts detrimental to overall health. Though previous research indicates a link between gut microbiota and cardiorespiratory fitness, it is unclear whether these findings are due to potential underlying effects %body fat or free-living activity energy expenditure (AEE). Microbe composition of fecal specimens from 37 breast cancer survivors were determined using 16S microbiome analyses. Individual-sample microbiota diversity (α-diversity) and between-sample community differences (β-diversity) were examined. Peak oxygen uptake (V̇O$_{\textrm{2peak}}$) was estimated from a graded exercise test (GXT) consistent with the modified-Naughton protocol, in which, exercise terminates at 85% age-predicted heart rate max (HR$_{\textrm{max}}$). AEE was measured over 10-days using doubly-labeled water wherein %body fat was calculated from total body water. Pearson correlations revealed α-diversity indices (Chao1, Observed Species, PD Whole Tree, Shannon) positively associated with V̇O$_{\textrm{2peak}}$ (r = 0.34 to 0.51; p < 0.05) whereas %HR$_{\textrm{max}}$ during Stages 1–4 of the GXT ($r$ = −0.34 to −0.50; $p$ < 0.05) and %body fat ($r$ = −0.32 to −0.41; $p$ < 0.05) were negatively associated with the same α-diversity indices. Multiple linear regression models showed V̇O$_{\textrm{2peak}}$ accounted for 22% and 26% of the variance in taxonomic richness (Observed Species) and phylogenic diversity after adjustment for %body fat and menopausal status. Unweighted UniFrac (β-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 cardiorespiratory fitness, not physical activity, is a superior correlate of gut microbiota diversity.