Age-Related Changes of Plasma Bile Acid Concentrations in Healthy Adults—Results from the Cross-Sectional KarMeN Study

Abstract

Bile acids (BA) play an important role in lipid metabolism. They facilitate intestinal lipid absorption, and BA synthesis is the main catabolic pathway for cholesterol. The objective of this study was to investigate associations of age, sex, diet (fat intake) and parameters of lipid metabolism (triglycerides, LDL, HDL, body fat content) with fasting plasma BA concentration of healthy individuals. Fasting plasma samples from a cross-sectional study were used to determine the concentrations of 14 BA using an LC-MS stable isotope dilution assay. Triglycerides, LDL and HDL were analyzed by standard clinical chemistry methods and body fat content was measured with a DXA instrument. The dietary fat intake of the 24 h period prior to the sampling was assessed on the basis of a 24 h recall. Subsequent statistical data processing was done by means of a median regression model. Results revealed large inter-individual variations. Overall, higher median plasma concentrations of BA were observed in men than in women. Quantile regression showed significant interactions of selected BA with age and sex, affecting primarily chenodeoxycholic acid and its conjugates. No associations were found for LDL and the amount of fat intake (based on the percentage of energy intake from dietary fat as well as total fat intake). Additional associations regarding body fat content, HDL and triglycerides were found for some secondary BA plasma concentrations. We conclude that age and sex are associated with the fasting plasma concentrations. Those associations are significant and need to be considered in studies investigating the role of BA in the human metabolism.

Bile acids and bariatric surgery

“…Given that obesity and insulin resistance are generally highly correlated, this apparent disconnect between bile acid concentrations and body mass is paradoxical. Further complicating the study of these phenomena in obesity are the confounders of age and sex (Prinz et al, 2015; Xie et al, 2015), both of which appear to influence circulating bile acid concentrations and lead to significant inter-individual variability (Frommherz et al, 2016). Moreover, longitudinal data has actually showed that weight loss leads to lower bile acid concentrations in the plasma.…”

Bile acids and cardiovascular function in cirrhosis

“…Hence, cirrhotic patients can have serum concentrations well above 100 μmol/L, 20,21 whereas the normal range of bile acids in fasting human adults is 2-15 μmol/L depending on age and gender. 22 Furthermore, there also appears to be a shift towards lower ratios of the trihydroxy to dihydroxycholanic acids as well as glycine to taurine conjugates. So far, however, the lack of significant diagnostic or prognostic benefit has discouraged the adoption of serum BA measurement as part of the routine work-up in patients with liver disease.…”

The role of nutrition in influencing mechanisms involved in environmentally mediated diseases

“…However, serum triglyceride (TG) and high-density lipoprotein (HDL-C) concentrations remained unchanged during the study. It is possible that these lipid changes are related in part to bile acid metabolism, because associations between body fat content, HDL and triglycerides and some secondary bile acid plasma concentrations were found in healthy adults (21). …”