Effects of fat and carbohydrate meals on colonic motor response

Background-Ingestion of a meal stimulates colonic motility. It is unclear w hether the nutrient composition of a meal affects colonic motor response. Aims--To investigate and compare the effects of a predominantly fat or carb ohydrate meal on colonic motility. Methods--In 18 healthy subjects, ambulatory colonic manometry was performed by placing a six sensor, solid state probe from the mid-transverse colon t o the rectum. In a randomised, crossover design, 10 and 27 hours after prob e placement, subjects received 4.18 MJ meals containing 60% calories from f at or carbohydrate sources. Preprandial and postprandial pressure activity and motor patterns were evaluated. Results--Both meals induced phasic activity with a greater area under the c urve (p<0.03) in the first postprandial hour, compared with the control per iod. Fat induced motor activity persisted longer (p<0.05) than that of the carbohydrate meal, but the onset of motor response was slower (p<0.001). Al though both meals induced more (p<0.001) propagating pressure waves, only t he fat meal induced more (p<0.05) simultaneous and retrograde waves. After both meals, 50% of subjects exhibited high amplitude (more than 103mm Hg), prolonged duration (more than 13 seconds) propagating waves. Both meals ind uced greater activity (p < 0.05) in the transverse/descending colon than in the rectosigmoid colon. Conclusions-Carbohydrate meals induce colonic motor response, but the effec ts are short lived when compared with fat meals. The prolonged, segmental, and retrograde phasic activity induced by the fat meal may delay colon tran sit. Thus meal composition influences colonic motor response.