Effects of lauric acid on upper gut motility, plasma cholecystokinin and peptide YY, and energy intake are load, but not concentration, dependent in humans

Abstract

Animal studies suggest that the effects of fatty acids on gastric emptying and pancreatic secretion are both concentration and load dependent, while their suppressive effect on energy intake is only load dependent. We postulated that, in humans, the modulation of antropyloroduodenal pressure waves, plasma cholecystokinin (CCK) and peptide YY (PYY) concentrations and energy intake by intraduodenal lauric acid, a fatty acid with 12 carbon atoms ('C12') would be load, but not concentration, dependent. Two groups of 12 healthy males were each studied on three separate occasions in double-blind randomized fashion. Antropyloroduodenal pressure waves, plasma CCK and PYY, and appetite perceptions were measured during intraduodenal infusions of C12 at (1) different loads of (i) 0.2, (ii) 0.3 and (iii) 0.4 kcal min(-1) (all 56 mM) for 90 min, and (2) different concentrations of (i) 40, (ii) 56 and (iii) 72 mM (all 0.4 kcal min(-1)) for 60 min. Energy intake at a buffet meal consumed immediately following each infusion was quantified. Suppression of antral and duodenal pressure waves, stimulation of pyloric pressure waves, stimulation of plasma CCK and PYY, and suppression of energy intake, were related to the load of C12 administered (r>0.65, P<0.05). In contrast, there were no concentration-dependent effects of C12 on any of these parameters. In conclusion, in humans, the effects of intraduodenal C12 on antropyloroduodenal motility, plasma CCK and PYY and energy intake appear to be related to load, but not concentration, at least at the loads and concentrations evaluated.

Figure 1. Basal pyloric pressure and isolated pyloric pressure waves

Basal pyloric pressure during intraduodenal infusion of C12 at different loads (0.2, 0.3 and 0.4 kcal min⁻¹, all at 56 mm) for 90 min (A), and different concentrations (40, 56 and 72 mm, all at 0.4 kcal min⁻¹) for 60 min (B). Number of isolated pyloric pressure waves during intraduodenal infusion of C12 at different loads (0.2, 0.3 and 0.4 kcal min⁻¹, all at 56 mm) for 90 min (C), and different concentrations (40, 56 and 72 mm, all at 0.4 kcal min⁻¹) for 60 min (D). *C12(0.4) and C12(0.3) versus C12(0.2), P < 0.001. Data are means ±s.e.m. (n = 12).

Figure 2. Plasma cholecystokinin and peptide YY concentrations

Plasma concentrations of cholecystokinin (CCK) during intraduodenal infusion of C12 at different loads (0.2, 0.3 and 0.4 kcal min⁻¹, all at 56 mm) for 90 min (A), and different concentrations (40, 56 and 72 mm, all at 0.4 kcal min⁻¹) for 60 min (B). Plasma concentrations of peptide YY (PYY) during intraduodenal infusion of C12 at different loads (0.2, 0.3 and 0.4 kcal min⁻¹, all at 56 mm) for 90 min (C), and different concentrations (40, 56 and 72 mm, all at 0.4 kcal min⁻¹) for 60 min (D). *C12(0.4) and C12(0.3) versus C12(0.2), P < 0.01; #C12(0.4) versus C12(0.3), P < 0.05. Data are means ±s.e.m. (n = 12).