Publication no. C-2003-0414-04R |  VIEW ARTICLE

In Vitro Binding of Bile Acids by Rice Bran, Oat Bran, Barley and beta-Glucan Enriched Barley.

T. S. Kahlon (1,2) and C. L. Woodruff (1). (1) Western Regional Research Center, USDA-ARS, Albany, CA 94710. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. (2) Corresponding author. Phone: 510-559-5665, Fax 510-559-5777. E-mail: <tsk@pw.usda.gov> Cereal Chem. 80(3):260-263. Accepted November 19, 2002. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Association of Cereal Chemists, Inc., 2003.

The in vitro bile acid binding by rice bran, oat bran, dehulled barley, and beta-glucan enriched barley was determined using a mixture of bile acids at a duodenal physiological pH of 6.3. Six treatments and two blank incubations were conducted testing substrates on an equal protein basis. The relative in vitro bile acid binding of the cereal brans on an equal total dietary fiber (TDF) and insoluble dietary fiber (IDF) basis considering cholestyramine as 100% bound was rice bran 45 and 49%; oat bran 23 and 30%; dehulled barley 33 and 57%; and beta-glucan enriched barley 20 and 40%, respectively. Bile acid bindings on equal protein basis for the respective cereals were 68, 26, 41, and 49%. Bile acid binding by rice bran may account to a great extent for its cholesterol-lowering properties, while bile acid binding by oat bran suggests that the primary mechanism of cholesterol lowering by oat bran is not due to the bile acid binding by its soluble fiber. Bile acid binding was not proportional to the soluble fiber content of the cereal brans tested. Except for dehulled barley, bile acid binding for rice bran, oat bran, and beta-glucan enriched barley appear to be related to their IDF content. Highest relative bile acid binding values for rice bran and beta-glucan enriched barley were observed on an equal protein basis, whereas highest values for dehulled barley were based on IDF. Data suggest that of all four cereals tested, bile acid binding may be related to IDF or protein anionic, cationic, physical and chemical structure, composition, metabolites, or their interaction with active binding sites.