Search

Background/aims: Dietary fiber can stimulate intestinal epithelial cell proliferation. The aim of this study was to resolve the different roles of fermentation and intraluminal viscosity on this trophic action and to investigate reported interactions between fiber and dietary fat., Methods: Conventional and germfree mice were fed guar gum in combination with low- or high-lipid diets for 2 weeks, and crypt cell production rates were determined., Results: Guar gum significantly stimulated proliferation in the small intestine, especially when combined with fat. Lipid itself also stimulated proliferation in the small intestine and had a direct trophic effect in the cecum and colon of the germfree mice. Fiber markedly stimulated proliferation in the cecum and colon but only in the conventional group. Interactions between lipid and bacteria and between guar gum and bacteria were also observed in the small intestine., Conclusions: Guar gum has a trophic effect in the small bowel, probably related to viscosity, in addition to its fermentation-related actions in the colon. Positive interaction with lipid may be associated with delayed absorption. Lipid also has its own direct actions on small bowel mucosal proliferation, which are attenuated by the presence of bacteria.

The effects of corn oil, guar gum and cellulose on mucosal proliferation were investigated in rats. Animals were allocated to three groups and fed a fiber-free diet or diets containing 100 g/kg of cellulose or guar gum. Each group was subdivided to receive corn oil at 40 or 80 g/kg. The crypt cell production rate (CCPR) was determined after 28 d. Consumption of guar gum or corn oil led to greater CCPR in the ileum and cecum. In a second experiment, animals were allocated to two groups and fed diets containing either cellulose or guar gum (100 g/kg). Each group was again subdivided to receive either corn oil (80 g/kg) or minimal lipid (linolenic acid, 10 g/kg). The trophic effect of guar gum occurred even in the low lipid-fed group, indicating that guar gum exerts a positive effect on cell turnover independently of any interaction with luminal lipid. However, the highest CCPR occurred in animals fed guar gum and corn oil. Postprandial enteroglucagon and gastrin concentrations were highest in animals fed both guar gum and corn oil. Thus, corn oil and guar gum exert independent trophic effects on the intestinal mucosa. The combination of effects led to a three- to four-fold increase in colon mucosal CCPR.