The effect of a fibre free and fibre supplemented polymeric enteral diet on normal human bowel function

Abstract

Although the effects of dietary fibre in a normal diet on intestinal function are well known, the effects of supplementing enteral diet with fibre on intestinal function are not so clear. The aims of the present study were two fold: firstly to compare intestinal function during ingestion of a self selected diet and fibre free polymeric enteral diet and secondly to investigate the effect of adding the fibre source, soy polysaccharide to the same polymeric diet, on bowel function. Six healthy subjects were randomly assigned to 3 treatment periods (7 days) of a self selected diet (SSD), 2 l polymeric enteral diet (ED), or 2 l of the same polymeric enteral diet supplemented with 20 g/l of soy polysaccharide fibre (SPED). Parameters measured were bowel frequency/day, mean daily wet stool weights and whole gut transit time. Highest stool wet weights (g/24 h ± SEM) were obtained from subjects consuming a SSD (180.3 ± 30.6). This was significantly higher (p < 0.02) than those consuming an ED (81.9 ± 14.5) but not a SPED (123 ± 22.3). Whole gut transit (h ± SEM) on a SSD (47 ± 5.9) was significantly (p < 0.05) quicker than on an ED (73 ± 4.9), but not significantly different from those ingesting a SPED (54 ± 5.5). Bowel frequency/day (± SEM) in subjects consuming a SPED (1.0 ± 0.1) was significantly (p < 0.02) higher than in subjects ingesting an ED (0.8 ± 0.1) but was not significantly different when compared to a SSD (1.0 ± 0.2). We conclude that ingestion of an ED results in significantly longer whole gut transit time, significantly decreased daily stool wet weights and decreased bowel frequency when compared to a SSD. The ingestion of 30 g of soy polysaccharide in a polymeric enteral diet not only tends to normalise whole gut transit time and daily stool wet weights, but also significantly increases bowel frequency when compared with values seen during the consumption of a fibre free polymeric enteral diet.