Abstract

The aim of this study was to investigate the association between cardiorespiratory fitness and gut microbiota composition in premenopausal women. The participants consisted of 71 premenopausal Finnish women (aged 19–49 years). Gut microbiota were analyzed using flow cytometry, 16S rRNA gene hybridization and DNA-staining. Maximum oxygen uptake (VO₂ₘₐₓ) was assessed by respiratory gas analyzer and body composition by Bioimpdance. We found that participants with low VO₂ₘₐₓ had lower Bacteroides, but higher Eubacterium rectale-Clostridium coccoides than the high VO₂ₘₐₓ group (p < 0.05 for all). VO₂ₘₐₓ was inversely associated with EreC (r = −0.309, p = 0.01) but not with other bacteria. VO₂ₘₐₓ also negatively correlated with fat% (r = −0.755, p < 0.001), triglycerides (r = −0.274, p = 0.021) and leptin (r = −0.574, p < 0.001). By contrast, EreC was positively associated with fat% (r = 0.382, p = 0.002), dietary fat intake (r = 0.258, p = 0.034), triglycerides (r = 0.390, p = 0.002) and leptin (r = 0.424, p = 0.001), but negatively with carbohydrate intake (r = −0.252, p = 0.034) and HDL (r = −0.26, p = 0.028). After adjusting for age and dietary intake, all the significant associations remained. However, after adjusting for fat%, the associations between VO₂ₘₐₓ and EreC disappeared. Our results suggest that cardiorespiratory fitness is associated with gut microbiota composition, independent of age and carbohydrate or fat intake. The association between VO₂ₘₐₓ and EreC, however, appears to be mediated by body fatness.