Dietary Fibers Affect Viscosity of Solutions and Simulated Human Gastric and Small Intestinal Digesta

Abstract

Two experiments were conducted to determine the viscosities of both soluble and insoluble dietary fibers. In Expt. 1, corn bran, defatted rice bran, guar gum, gum xanthan, oat bran, psyllium, soy hulls, stabilized rice bran, wheat bran, wood cellulose, and 2 methylcellulose controls (Ticacel 42, Ticacel 43) were hydrated in water overnight at 0.5, 1, 1.5, or 2% concentrations. In Expt. 2, guar gum, oat bran, psyllium, rice bran, wheat bran, and wood cellulose were subjected to a 2-stage in vitro gastric and small intestinal digestion simulation model. Viscosity was measured every 2 and 3 h during gastric and small intestinal simulation, respectively. Viscosities in both experiments were measured at multiple shear rates. Viscosities of all fiber solutions were concentration- and shear rate-dependent. Rice brans, soy hulls, and wood cellulose had the lowest viscosities, whereas guar gum, psyllium, and xanthan gum had the highest viscosities, regardless of concentration. During gastric simulation, viscosity was higher (P < 0.05) at 4 h than at 0 h for guar gum, psyllium, rice bran, and wheat bran. During small intestinal simulation, viscosities were higher (P < 0.05) between 3 and 9 h compared with 18 h for guar gum, oat bran, and rice bran. Guar gum, psyllium, and oat bran exhibited viscous characteristics throughout small intestinal simulation, indicating potential for these fibers to elicit blood glucose and lipid attenuation. Wheat and rice brans and wood cellulose did not exhibit viscous characteristics throughout small intestinal digestion; thus, they may be beneficial for laxation.

By-products of Rice Processing: An Overview of Health Benefits and Applications

“…They are not digested by human pancreatic or brush border enzymes and therefore are not expected to be fully absorbed. However, their consumption does help to control blood glucose levels and lipid concentrations by enhancing the viscosity of the gastrointestinal contents [46].…”

Ingestion of Gelatinized Potato Starch Containing a High Level of Phosphorus Decreases Serum and Liver Lipids in Rats

“…Chylomicron plays a role to the transfer of lipids absorbed in the small intestine into the liver. Some water-soluble dietary fibers, such as guar gum, exhibit a highly viscous character in the human gastrointestinal tract 19) . Furthermore, it has been reported that the ingestion of guar gum markedly reduces blood glucose levels and improves insulin sensitivity in STZ diabetic rats 20) , and induces a lipid-lowering effect in cholesterol-fed rats 21) .…”

A review on Oat (Avena sativa L.) as a dual-purpose crop

“…Bladder and bowel conditions, intestinal colic and bedwetting have all been helped by soaking in a bath of Oat Straw. These effects of oat β-glucan were well reviewed by Mälkki and Virtanen (2001), Ulmius et al (2011), Wang et al (2002 and Dikeman et al (2006).…”