Relationship between circulating biliary acids and functional capacity in patients with severe obesity

Abstract Background Obesity is a disease with a significant impact on the cardiovascular system and functional capacity. The multiple underlying mechanisms are not fully understood. Recent evidence has linked circulating bile acid (BA) homeostasis to cardiovascular health. Purpose This study aims to investigate the potential correlation between circulating BA and functional capacity parameters in a population of patients with severe obesity, including a subgroup undergoing bariatric surgery. Methods An observational study was conducted on 60 patients with severe obesity, of whom 21 underwent bariatric surgery (BS). All patients underwent a maximal cardiopulmonary exercise test, maximal handgrip strength test, as well as the serum dosage of primary (free and conjugated) and secondary BA. Statistical analysis: Spearman’s correlation and non-parametric Wilcoxon signed-rank test were performed. Results In 60 patients with severe obesity (mean BMI 44.8±6.8 kg/m2, mean age 46±10 years, 56.7% female) mean VO2peak/Kg was 19.6±4.2 mL/min/Kg), 67.9% of subjects had a handgrip strength (dominant arm) below the 50th percentile. VO2peak/Kg was slightly related only to taurine conjugated deoxycholic acid (rho -.260, p.045). A significant correlation (p0.05) was observed between the percentage of the predicted O2 pulse (VO2/Heart rate) at peak of exercise, as indirect expression of left ventricular compliance and contractility, and several circulating BA. In particular, O2 pulse was inversely related to total secondary BA (rho -.371), total free secondary BA (rho -.269) and total chenodeoxycholic acids (rho -.268). Peripheral oxygen saturation at peak of exercise was also inversely and significantly (p0.05) related to total primary BA (rho -.302), total free primary BA (rho -.300) and total chenodeoxycholic acids (rho -.268). In contrast, handgrip strength values were directly and significantly (p 0.05) related to glycine conjugated deoxycholic and urso-deoxycholic acid (rho .428 and .397), total secondary BA (rho .432), total free secondary BA (rho .404) and Total non-12α-hydroxylated BA (rho .413). After BS (mean follow-up 11.1±2.0 months), the decrease in absolute VO2 (on average -7.5%) was directly related to deoxycholic acid, and total free secondary BA as well as indirectly related to total taurine and glycine conjugated BA, total primary and total free secondary BA. The increase in VO2/Kg (on average +35.2%) was indirectly related to total primary and total glycine-conjugated cholic acid. Finally, the increase in O2 pulse was indirectly correlated to total primary, total glycine-conjugated cholic acid and Total non-12α-hydroxylated BA. Conclusions BA are correlated with handgrip strength values, several cardiopulmonary parameters and their changes after BS. BA may, thus, be involved in functional limitations in obesity and, in particular, in cardiovascular and peripheral limitations. This observational study can serve as a basis for more in-depth research.