Inhibition of postprandial colonic motility after ingestion of an amino acid mixture.

Previous studies suggested that the ingestion of a mixture of amino acids inhibited the fat-stimulated increase in colonic motility. This study determine the effect of the ingestion of an amino acid mixture on the postprandial distal colonic spike potential (SP) response to a standard 1000-calorie meal in normal subjects and in patients with the irritable bowel syndrome. The distal colonic response was measured following a standard meal with and without the preadministration of a protein hydrolysate solution. After the meal, normal subjects had their maximum response within the first 30-min postprandial period (41.0 +/- 6.3 SP/30 min). Spike activity returned to fasting activity by 60 min. Most patients with irritable bowel syndrome did not have a significant early postprandial distal colonic spike response (P > 0.05), but all patients had a large late increase in spike activity occurring 60-90 min postprandially (50.0 +/- 5.0 SP/30 min) (P < 0.001). Ingestion of the protein hydrolysate solution prior to the meal resulted in suppression of the early colonic spike response in normal subjects (P < 0.01) and the late colonic spike response in the irritable bowel patients (P < 0.01). This study suggests that amino acids can modulate postprandial colonic motility and that dietary alteration may be beneficial in the irritable bowel syndrome.