Short-Chain Fatty Acids and Human Colonic Function: Roles of Resistant Starch and Nonstarch Polysaccharides

Abstract

Resistant starch (RS) is starch and products of its small intestinal digestion that enter the large bowel. It occurs for various reasons including chemical structure, cooking of food, chemical modification, and food mastication. Human colonic bacteria ferment RS and nonstarch polysaccharides (NSP; major components of dietary fiber) to short-chain fatty acids (SCFA), mainly acetate, propionate, and butyrate. SCFA stimulate colonic blood flow and fluid and electrolyte uptake. Butyrate is a preferred substrate for colonocytes and appears to promote a normal phenotype in these cells. Fermentation of some RS types favors butyrate production. Measurement of colonic fermentation in humans is difficult, and indirect measures (e.g., fecal samples) or animal models have been used. Of the latter, rodents appear to be of limited value, and pigs or dogs are preferable. RS is less effective than NSP in stool bulking, but epidemiological data suggest that it is more protective against colorectal cancer, possibly via butyrate. RS is a prebiotic, but knowledge of its other interactions with the microflora is limited. The contribution of RS to fermentation and colonic physiology seems to be greater than that of NSP. However, the lack of a generally accepted analytical procedure that accommodates the major influences on RS means this is yet to be established.

Effect of popping on sorghum starch digestibility and predicted glycemic index

“…As puffing of the grains is expected to disrupt the sub-cellular structure of the endosperm, the penetration of digestive enzymes becomes easier, and consequently, increases the starch content marginally. Unprocessed sorghum contains native starch which is resistant to digestion (Topping and Clifton 2001) and hence the resistant starch content is high. Severe heat treatment like autoclaving has been reported to reduce the resistant starch content (Skrede et al 2001).…”

Acetylation of the Entamoeba histone H4 N-terminal domain is influenced by short-chain fatty acids that enter trophozoites in a pH-dependent manner

“…E-mail address: eichid01@med.nyu.edu. 1 Current address: National Academy of Sciences, Washington, D.C. USA (SCFA) acetate, propionate and butyrate, serve directly as an energy source for the host and other bacteria, (Cummings et al, 1987;Topping and Clifton, 2001), and indirectly define microbial habitation boundaries along the length of the intestine. For example, the relatively small amounts of SCFA present in the distal small intestine can up-regulate virulence genes in pathogenic species of Salmonella and Pseudomonas, allowing them to colonize that region of the intestine (Levinson, 1973;Durant et al, 2000).…”

Gastrointestinal responses following acute and medium term intake of retrograded resistant maltodextrins, classified as type 3 resistant starch

“…During the last decade, there has been an intensified interest in the role of resistant starch (RS) being a well-fermentable digestion-resistant carbohydrate, having the potential to modify gut microflora and gut luminal contents in a potentially beneficial way for maintaining a healthy colon function (Asp et al, 1997;Kleessen et al, 1997;Bird et al, 2000;Haralampu, 2000;Topping and Clifton, 2001;Brouns et al, 2002). The increasing knowledge of starch digestion in humans has allowed a new classification of types of RS that has now been commonly accepted (Englyst et al, 1992Champ et al, 2003).…”

“…RS is supposed to contribute to colonic health through effects on gut flora, intestinal pH reduction, secondary bile acids reduction, elevated butyrate production and reductions in putrefactive protein fermentation as well as in luminal ammonia concentrations. Although these effects are generally supposed to beneficially impact on health, not all studies show a positive outcome on measured clinical endpoints (Edwards et al, 1995;Hylla et al, 1998;Topping and Clifton, 2001). Type 4 RS may differ in fermentation behaviour depending on its modified molecular structure.…”