Associations between Aerobic Capacity, Hepatic Bile Acid Synthesis and Fecal Bile Acid Concentration in Humans

Abstract

High aerobic capacity protects against a wide range of metabolic diseases and associates with changes in liver metabolism including enhanced mitochondrial function, although mechanisms remain unknown. Bile acids are now seen as active players in metabolic regulation. We have previously found that rodents with high aerobic capacity potentially have the ability to divert excess acetyl‐CoA away from de novo lipogenesis and toward bile acid synthesis and fecal excretion. To determine if the fitness‐bile acid association manifests in humans, in a preliminary study we tested the hypothesis that female subjects screened for high aerobic fitness (Hi‐Fit, n=10) (VO2peak>45 ml/kg/min) also have increased hepatic bile acid synthesis and fecal excretion compared to those matched for age and body mass with low aerobic fitness (Lo‐Fit, n=10) (VO2peak<35 ml/kg/min). Diet intake, activity level, stool, and blood were measured at baseline before receiving a 1 week standardized, weight‐maintaining eucaloric diet. After the 1week standardized diet, stool and blood were again measured, and an Oral Glucose Tolerance Test (OGTT) was performed. Hi‐fit women tended to have higher bile acid synthesis via measured serum 7α‐hydroxy‐4‐cholesten‐3‐one (C4), a clinically proven surrogate of bile acid production, both during fasting (p≈0.16) and following the OGTT (p≈0.06). However, no significant differences in circulating or fecal bile acid concentrations were found. Future research should consider using direct tracer measurements of bile acid synthesis and excretion, and the utilization of 24 hr+ fecal bile acid measures to quantify total production and excretion.Support or Funding InformationUSDA‐Agricultural Research Service Project 6026‐51000‐010‐05SThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.