How do fiber-supplemented formulas affect antroduodenal motility during enteral nutrition? A comparative study between mixed and insoluble fibers.

BACKGROUND Fiber supplementation during enteral nutrition has been recommended, but the effect of soluble compared with insoluble fiber supplements on antroduodenal motility is unknown. OBJECTIVE The objective of this study was to compare antroduodenal motor patterns in 8 healthy volunteers during and after gastric infusion of 3 different diets: a fiber-free diet, an insoluble-fiber diet, and a mixed-fiber diet (50% soluble fiber and 50% insoluble fiber). DESIGN Manometric studies with the 3 different diets (2100 kJ) were performed in random order. Antroduodenal motility was monitored continuously for 6 h by using a pneumohydraulic system to calculate the number, amplitude, and duration of the pressure waves; the area under the curve (AUC); and the percentage of time occupied by motor activity before, during, and after each type of infusion. Variations in antral areas were measured by ultrasonography. RESULTS The gastric motor response was significantly higher, whatever the diet, in the distal antral recording site than in the 2 more proximal sites. In the proximal but not the distal antrum, the number of waves, the AUC, and the percentage of time occupied by motor activity were higher (P: < 0.04) with the mixed-fiber than with the insoluble-fiber diet. No significant differences in variations of antral area were observed among the 3 diets. In the duodenum, motor variables were not significantly different among the 3 diets. CONCLUSIONS A gastric infusion induced a greater motor response in the distal than in the proximal antrum. A mixed-fiber diet was associated with significantly greater proximal antral motility than was an insoluble-fiber diet. There was no significant difference among the 3 formulas in duodenal motor variables or in variations in antral area as measured by ultrasound.