Comparison of the small bowel motor response to solid and liquid meals in man

Interdigestive motor activity has been studied extensively both in the human and canine small intestine. The more irregular postprandial pattern, however, has rarely been studied. In particular, physiological studies in humans are lacking. Thus it is unknown whether the physical state of a meal affects the duration of the postprandial motor activity or contractile activity during the postprandial period. 8 healthy male volunteers, aged 19-38 years, underwent a single ambulatory 24-hour manometry study. During the study, volunteers had two physiological meals. The solid meal consisted of pasta with vegetables, and the liquid meal was a vanilla milk drink. The two meals were both palatable, isocaloric (660 kcal) and had an identical fat content (32%). Recordings were analyzed visually for phase III of the migrating motor complex and a validated computer program calculated the mean frequency and amplitude of contractions as well as the mean area under the curve (AUC). The postprandial period was significantly shorter after the liquid meal compared to the solid meal (196 +/- 43 vs. 298 +/- 23 min; p < 0.04). During the postprandial period, the mean incidence of contractions (2.0 +/- 0.5 vs. 3.7 +/- 0.4 min(-1); p < 0.02) and the mean AUC (132 +/- 32 vs. 236 +/- 27 mm Hg x s x min(-1); p < 0.02) were significantly lower after the liquid meal. The mean amplitude of contractions during the total postprandial period, however, was not significantly different between the two test meals (19.3 +/- 0.6 vs. 18.6 +/- 0.8 mm Hg). We conclude that human small bowel motor activity differs markedly between solid and liquid meals. Thus the postprandial pattern persists longer after solid meals, and this may have been due to the slower gastric emptying of solids as opposed to liquids. Furthermore the small bowel contracts far more frequently after solid meals.