Dietary Fibers VI: Binding of Fatty Acids and Monolein from Mixed Micelles Containing Bile Salts and Lecithin 1

Abstract

Mixed micelles were prepared containing sodium taurocholate, monolein dioleyl lecithin, cholesterol, and an equimolar mixture of palmitic, oleic, and linoleic acids. These were incubated with commercial bile acid-sequestering resins, cholestyramine and DEAE-Sephadex, or various dietary fibers and fiber components including wheat bran, cellulose, alfalfa, lignin, and two viscosity grades of guar gum. Binding of monolein and fatty acids was determined as the difference between the radioactivity of the added micellar component, and that recovered in the centrifugal supernatant after incubation. In general, the extent of monoglyceride or fatty acid sequestration was characteristic and reproducible for each binding agent. Cholestyramine and DEAE-Sephadex essentially quantitatively bound monoglycerides and all three fatty acids from micellar medium. Low- and high-viscosity grades of guar gum sequestered 15-23% of the monolein and 32-33% of the fatty acids, showing a significant preference for linoleic acid in each case. Alfalfa fiber removed about 18% of the micellar monoglyceride and mixed fatty acids, again showing some preference for the polyunsaturated acid. Lignin, the hydrophobic component of dietary fibers, sequestered about 13% of the available lipids and displayed an apparent preference for oleic acid. Wheat bran and cellulose showed little affinity for micellar lipids binding about 11 and 4.7%, respectively. These data on resin and fiber sequestration of micellar fatty acids and monoglycerides compare favorably with the binding of other micellar components including phospholipid, bile salt, and cholesterol.