Comparative effects of intraduodenal infusions of lauric and oleic acids on antropyloroduodenal motility, plasma cholecystokinin and peptide YY, appetite, and energy intake in healthy men

Background: The regulation of gastrointestinal function and energy intake by fatty acids depends on their chain length. Animal studies suggest that lauric acid (C12) may have more potent suppressive effects on energy intake than does oleic acid (C18). Objective: We compared the effects of equicaloric loads of C 12 and C 18 on antropyloroduodenal (APD) motility, plasma concentrations of cholecystokinin (CCK) and peptide YY (PYY), appetite, and energy intake. Design: Thirteen healthy men (aged 20-46 y) were studied on 3 occasions in double-blind, randomized fashion. APD pressure waves, plasma hormones, and appetite perceptions were measured during 60-min intraduodenal infusions of 1) C12,2) C18, or 3) 0.9% saline as control (rate: 4 mL/min; energy load for C12 and C18: 0.4 kcal/min); between 60 and 90 min, the subjects consumed a meal. Energy intake at a buffet meal was quantified. Results: C12 and C 18 both reduced antral (P < 0.001) and duodenal (P < 0.01) pressure waves and stimulated isolated pyloric pressure waves (P < 0.01) and plasma CCK (P < 0.001), with no differences between them. Although C12 and C18 both increased basal pyloric pressure (P < 0.05), C 12 had a greater effect than did C 18 (P < 0.01). In contrast, although both C 12 and C 18 increased plasma PYY (P < 0.001), C 18 had a greater effect than C12. C 12, but not C 18, suppressed energy intake (P < 0.05). Conclusions: At the load administered, C12, but not C18, suppressed energy intake, and C 12 was a more potent stimulant of basal pyloric pressure. These discrepant effects are not apparently accounted for by changes in CCK or PYY secretion.