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Abstract

The effects of adaptation to two diets differing in the type of dietary fat on the circulating levels of secretin, cholecystokinin, and pancreatic polypeptide, were investigated in humans. A relationship with the results concerning gastric acid secretion and gastrin release previously described by us, was also examined. The study in volved 18 cholecystectomized subjects previously submitted to a 30-day adaptation period to diets containing olive (group O) or sunflower oil (group S) as the main fat source. During the experimental period, physiological stimulation was achieved by ingestion of 200 mL oleic acid- (group O) or linoleic acid enriched (group S) liquid mixed meals. Food ingestion did not induce no significant changes in plasma secretin concentration in any of the groups, and no signijicant differences were observed between them for basal and postprandial situations. Plasma cholecystokinin le veIs were signijicantly higher in group O throughout the 30-120 min postprandial periodo The type of dietary fat affected the pancreatic polypeptide response to food, since values in group O were significantly higher than in group S at any point during the postprandial period, thus, despite of significant release in both grollps after the meal. lt is suggested that endogenous cholecystokinin may be responsible for the attenuated gastric acid secretory response and the suppression of serum gastrin previously observed in the subjects of group O, through a somatostatin-mediated (paracrine) or peptide YY-mediated (endocrine) mechanism. Secretin does not seem to be in volved in the fat-induced inhibition of human gastric acid secretion, and a role for pancreatic polypeptide is doubtful.