Plasma Levels of Bile Acids Are Related to Cardiometabolic Risk Factors in Young Adults

Abstract

Context: Bile acids (BA) are known for their role in intestinal lipid absorption and can also play a role as signaling molecules to control energy metabolism. Prior evidence suggests that alterations in circulating BA levels and in the pool of circulating BA are linked to an increased risk of obesity and a higher incidence of type 2 diabetes in middle-aged adults.

Objective: We aimed to investigate the association between plasma levels of BA with cardiometabolic risk factors in a cohort of well-phenotyped, relatively healthy young adults.

Methods: Body composition, brown adipose tissue, serum classical cardiometabolic risk factors, and a set of 8 plasma BA (including glyco-conjugated forms) in 136 young adults (age 22.1 ± 2.2 years, 67% women) were measured.

Results: Plasma levels of chenodeoxycholic acid (CDCA) and glycoursodeoxycholic acid (GUDCA) were higher in men than in women, although these differences disappeared after adjusting for body fat percentage. Furthermore, cholic acid (CA), CDCA, deoxycholic acid (DCA), and glycodeoxycholic acid (GDCA) levels were positively, yet weakly associated, with lean body mass (LBM) levels, while GDCA and glycolithocholic acid (GLCA) levels were negatively associated with 18F-fluorodeoxyglucose uptake by brown adipose tissue. Interestingly, glycocholic acid (GCA), glycochenodeoxycholic acid (GCDCA), and GUDCA were positively associated with glucose and insulin serum levels, HOMA index, low-density lipoprotein cholesterol, tumor necrosis factor alpha, interleukin (IL)-2, and IL-8 levels, but negatively associated with high-density lipoprotein cholesterol, ApoA1, and adiponectin levels, yet these significant correlations partially disappeared after the inclusion of LBM as a confounder.

Conclusion: Our findings indicate that plasma levels of BA might be sex dependent and are associated with cardiometabolic and inflammatory risk factors in young and relatively healthy adults.

Keywords: biomarkers; brown adipose tissue; cardiometabolic risk; dyslipidemia; insulin resistance.

Figure 1.

Correlations between plasma levels of bile acids with body composition and brown adipose tissue parameters in young adults (n = 133). Every colored box represents a significant correlation coefficient (all P < 0.05), whereas invisible (white) boxes represent nonsignificant correlations. Values within the boxes express the r of Pearson coefficient. Bile acids concentration values were log₁₀ transformed. Abbreviations: BAT, brown adipose tissue; CA, cholic acid; CDCA, chenodeoxycholic acid; DCA, deoxycholic acid; GCA, glycocholic acid; GCDCA, glycochenodeoxycholic acid; GDCA, glycodeoxycholic acid; GLCA, glycolithocholic acid; GUDCA, glycoursodeoxycholic acid; SUV, standardized uptake value.

Figure 2.

Correlations between plasma levels of bile acids concentrations with cardiometabolic risk factors in young adults (n = 133). Every colored box represents a significant correlation coefficient (all P < 0.05), whereas invisible (white) boxes represent nonsignificant correlations. Values within the boxes represent the r of Pearson coefficient. All blood parameters were log₁₀ transformed. Abbreviations: ALP, alkaline phosphatase; ApoA1, apolipoprotein A1; ApoB, apolipoprotein B; CA, cholic acid; CDCA, chenodeoxycholic acid; DCA, deoxycholic acid; GCA, glycocholic acid; GCDCA glycochenodeoxycholic acid; GDCA, glycodeoxycholic acid; GGT, gamma-glutamyl transferase; GLCA, glycolithocholic acid; GTP, phosphoglycerate kinase; GUDCA, glycoursodeoxycholic acid; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol.