Page 34 - Human Bile Acid Metabolism: a Postprandial Perspective

Chapter 2
Results
Postprandial concentrations of TBA
Postprandial TBA concentrations increased with increasing meal fat content (post-test for linear trend, P < .001), peaked after 1–2 hours, and were higher in T2D patients vs NGT subjects (OGTT, low and medium fat meals, P < .05; high fat meal, P = .30) (Figure 1 and Table 1). Fasting concentrations of total, unconjugated, and amidated bile acids were marginally increased in T2D patients vs NGT subjects (Supplemental Table 1). A subgroup analysis revealed no differences in TBA and FGF19concentrations in metformin-treated patients vs patients treated with sulfonylureas and diet only (data not shown).
Postprandial concentrations of primary bile acids (CA and CDCA)
Postprandial total CA concentrations were dominated by glycine conjugates, which were higher in T2D patientsvs NGT subjects (Table 1 and Figure 2) after OGTT and low and medium fat meals, but not after the high fat meal.Other CA fractions did not differ between the two groups.In comparison with the other bile acids measured, glycine-conjugated CDCA was the dominating bile acid found postprandially (Figure 2). In both groups, a clear and positive effect of meal fat (post-test for linear trend, P < .001) was demonstrated, but no between-group differences were present. There was a tendency to higher taurine conjugates in NGT subjects, but this difference was not statistically significant (Supplemental Figure 4). Fasting concentrations of total and unconjugated CA and CDCA were comparable between groups, whereas glycine-conjugated CA and taurine-conjugated CA and CDCA were marginally higher in T2D patients vs NGT subjects (Table 1).
Postprandial concentrations of secondary bileacids (DCA and UDCA)
Postprandial DCA concentrations were markedly higher in T2D patients after all meal stimuli. These differences reflected unconjugated and glycine-conjugated bile acids and, to a lesser extent, taurine conjugates (Table 1 and Figure 2). Although postprandial UDCA concentrations were 5- to 10-fold lower relative to the other bile acids measured, a clear increase was demonstrated in T2D patients vs NGT subjects. As for DCA concentrations, this difference reflected increased unconjugated and glycine-conjugated UDCA. However, in both groups, taurine conjugates were very low. Again, meal fat content associated positively with bile acid concentrations (post-test for linear trend, P < .001). Fasting concentration of
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