Influence of various nutrients and their mode of application on plasma cholecystokinin (CCK) bioactivity.

CCK is known to be a major endocrine stimulant of the exocrine pancreas. However, the influence of various compositions of nutrients and their mode of administration on plasma CCK is still not clear. We therefore studied plasma CCK after either oral or intraduodenal administration of various solid and liquid diets. Plasma CCK was measured by bioassay. Nine healthy male volunteers received three different isocaloric diets via intraduodenal perfusion (1 kcal/ml; 300 ml/90 min). Diet A consisted of low-molecular oligopeptides (energy: protein 18%, fat 22%, carbohydrates 60%); diet B was a high molecular diet enriched with fat and fiber (protein 15%, fat 30%, carbohydrates 55%, fiber 1 g/100 ml); and diet C was a high molecular diet, poor in fat and fiber-free (protein 14%, fat 7%, carbohydrates 79%). All diets caused a rapid increase in plasma CCK, followed by a slow decrease. The highest CCK plasma values were achieved with diet B (8.4 +/- 1.6 pM); diets A and C led to similar, rather low plasma CCK values (A: 5.0 +/- 0.7 pM). Another five volunteers received the above-described liquid diets orally. Integrated CCK plasma values were similar for all oral liquid diets studied and not different from those seen after intraduodenal administration of the high-molecular high-fat diet B. Oral administration of a solid diet (ten volunteers) comparable to diet B in calories and nutrient composition caused a rather small and delayed increase in plasma CCK.(ABSTRACT TRUNCATED AT 250 WORDS)