Influence of starches of low digestibility on the rat caecal microflora

Abstract

1. Male Sprague-Dawley rats were fed on either a purified, fibre-free diet or a diet in which half the maize starch was replaced with uncooked amylomaize or potato starch (equivalent to 100 or 200 g amylase-resistant starch (ARS)/kg diet respectively). Changes in short-chain fatty acids (SCFA), pH, ammonia and a number of bacterial variables in caecal contents were then assessed.2. Both ARS supplements decreased caecal content pH by approximately 1–2 units, with an associated reduction in ammonia concentration. Potato starch significantly decreased the concentration of SCFA in the hind-gut, while amylomaize supplementation increased propionic and butyric acids but decreased the occurrence of minor, branched-chain fatty acids.3. Caecal bacterial biotransformation activities (β-glucosidase (EC3.2.1.21), β-glucuronidase (EC3.2.1.31), reduction ofp-nitrobenzoic acid, apparent ammonia formation) were consistently decreased by both ARS sources.4. The results demonstrate that amylase-resistant carbohydrate altered toxicologically important functions in the large-intestinal flora of the rat.

Intestinal mucosal morphometry and ileal epithelial renewal in conventional and germ-free rats fed an amylomaize starch diet

“…Modifications other than SCFA production have been observed in the large intestine of rats fed amylomaize starch including a significant decreased in bacterial activities of nitro-and azoreductase and [3-glucuronidase (Mallett et al, 1988) and altered bile acid bacterial transformation (Andrieux et al, 1989). Similar observations have also been reported for various other poorly digestible carbohydrates and have been related to the decrease in caecal pH in CV rats fed these carbohydrates and to a modification of the bacterial population in the large intestine (Andrieux et al, 1989).…”

The fermentation of lactulose in rats inoculated with Clostridium paraputrificum influences the activities of liver and intestinal xenobiotic‐metabolising enzymes

“…The glycolytic activities (b-glucosidase, b-glucuronidase and b-galactosidase) were assayed under aerobic conditions according to Mallet et al, 20 using speci®c substrates (galactoside, glucuronide or glucoside) linked with p-nitrophenol. The release of p-nitrophenol from the p-nitrophenylglycoside was evaluated by spectrophotometry at 400 nm.…”

Proliferation of Bifidobacteria by Oligosaccharides and Their Useful Effect on Human Health

“…Mallett et al (11) reported that the decrease in cecal branched-chain SCFA was associated with the reduction in cecal cancer-related enzyme activities in rats fed a low-digestible starch diet. Such changes may be due to the suppression of putrefactive intestinal bacteria and are desirable in preventing colon cancer .…”