The effect of osmolarity and caloric load on small bowel motility

Background: Although there is profound knowledge about cyclic fasting motility, the postprandial intestinal motor response is not well investigated. It is intriguing to speculate that nutrient composition alters small bowel motility significantly and, in a clinical setting, may account for adverse gastrointestinal symptoms in enteral nutrition (EN). We aimed to assess the impact of different caloric loads and osmolarities of EN on human jejunal motility.

Methods: Sixteen healthy subjects underwent a series of duodenal infusions of EN solutions, either with iso-osmolar solution with different caloric loads (1.32, 2.64, or 3.96 kcal min(-1)), or with solutions of different osmolarities with constant caloric loads (300, 600, or 1200 mosmol). Jejunal solid-state manometry was analyzed over 90 min both visually and using dedicated computer software.

Key results: All tested nutrient solutions were able to trigger conversion to a postprandial jejunal motility pattern after a mean lag phase of 9.4 + 2.3 min (P = NS between different nutrient solutions). Different caloric loads did not result in significant differences in small bowel motility. However, increasing osmolarities caused a significant inhibition of contractile and propagative activity.

Conclusions & inferences: Small bowel motility under duodenal infusion of nutrient solutions is not influenced by caloric load in a physiological range, whereas high osmolarities inhibit small bowel motility.