The trophic effect of dietary fibre is not associated with a change in total crypt number in the distal colon of XXXX .

@entity35 @entity2133 @entity6693 @entity194 @entity105 @entity3505 @entity694 @entity7522
Soluble fibres, such as guar gum, promote and @entity3505 bran or methylcellulose protect from chemically induced @entity694 , relative to the effect of a fibre-free diet in @entity35 . Mechanisms are poorly understood. Whereas all fibres are trophic to the colonic epithelium, the heterogeneity of effects on @entity105 may reflect different effects on the total number of crypts and, therefore, the size of the stem cell population. This study aimed to assess this hypothesis. @entity35 were fed one of fibre-free diets with or without 10% @entity3505 bran, methylcellulose or guar gum for 4 weeks. The distal colons were stained with @entity6693 and quantified for the number and density of crypts using an image analysis system. Epithelial proliferative kinetics was measured stathmokinetically. Methodology for quantifying crypts was valid and reproducible. @entity35 fed a fibre-free diet had @entity694 , as shown by a decrease in crypt column height and a lower mitotic index. Fibre supplementation prevented the @entity194 and was associated with @entity2133 areas that were 30-60% larger than those in the fibre-free group (P < 0.001, ANOVA), with the @entity7522 group being the largest (1.16 microm(2)). The crypt density of the fibre-free group was 16-19% greater than those in fibre fed groups (P + 0.006), due to the smaller size of the crypts. However, there was no difference in the total number of crypts across the four dietary groups (P > 0.1). Distal colons in all of the dietary groups contained approximately 10(5) crypts. In conclusion, although variation in the amount or type of dietary fibre exerts heterogeneous effects on the growth of the colonic epithelium and on @entity694 , the total number of crypts in the distal colon remains constant. It is, therefore, unlikely that fibres influence carcinogenic events by altering the size of the stem cell population.
