Effects of dietary supplements of wheat bran and cellulose on faeces and bowel function

In a study of bowel function in normal subjects wheat bran or cellulose was added to the diet for four weeks (16 g/day). Stool weight increased. Intestinal transit time did not significantly alter. Faecal bile acids did not increase but were diluted. It seems that the effect of these materials is to produce a bulky stool and that any symptomatic benefit they produce is secondary to this.