Medium chain triglycerides activate distal but not proximal gut hormones

Background and aims: Compared to long chain triglycerides (LCT), medium cha in triglycerides (MCT) are considered an attractive caloric source in malab sorptive diseases because of their favorable physico-chemical characteristi cs. The use of MCT is, however, limited by the occurrence of gastrointestin al symptoms such as diarrhoea. We have, therefore, investigated the effects of MCT and LCT on proximal (cholecystokinin; CCK) and distal (peptide YY; PYY) gut hormone secretion. Methods, Eight healthy volunteers participated ire four experiments perform ed in random order during continuous intraduodenal administration for 360 m in of a) saline (control); b) LCT 15 mmol/h; c) MCT 15 mmol/h (equimolar); d) MCT 30 mmol/h (equicaloric). Plasma CCK and PW were determined at regula r intervals (radioimmunoassay). Duodenocecal transit (DCTT) was measured by lactulose H-2 breath test. Results. DCTT during LCT (105 +/- 11 min) was not significantly different f rom saline (111 +/- 10 min). Both low dose MCT (54 +/- 5 min) and high dose MCT (61 +/- 6 min) significantly accelerated DCTT (P < 0.05). Plasma CCK i ncreased significantly (P < 0.05) during LCT but not during MCT or saline. PYY increased significantly(P < 0.05) not only during LCT, but also during low and high dose MCT but not during saline. Conclusions: Intraduodenal MCTs a) accelerate intestinal transit; b) do not stimulate CCK release; c) but stimulate release of the distal gut hormone PW. These results suggest that MCTs are not rapidly absorbed in the proxima l gut but probably reach the ileocolonic region and stimulate PW release. ( C) 1999 Harcourt Publishers Ltd.