Fermentable Dietary Fiber in Dried Products of Brown Algae and Their Effects on Cecal Microflora and Levels of Plasma Lipid in Rats

Abstract

The content of dietary fibers, laminaran and alginate, in 22 dried products of brown algae and their effects on cecal microflora and levels of plasma lipid in rats were surveyed. After washing with methanol, 0.1 N hydrochloride fractions (F1: crude laminaran and fucoidan), 1% sodium carbonate fractions (F2: crude alginate) and insoluble fractions (F3) were extracted from the algae using the ethanol precipitation method. F1, F2 and F3 ranged from about 1 to 22%, 10 to 67% and 3 to 59%, respectively, of dry matter. Laminaran was detected in only three products by bioassay using Clostridium ramosum. Laminaran content was the largest in arame Eicenia bicyclis. Fucoidan was not detected in arame by TLC. Diets containing 5% arame powder (AP) (whose content is too high for normal intake), 0.75% F1, 2.2% F2 and 1.5% F3 of arame, which are respectively dose equivalents to 5% of AP, were administered to male rats for seven days. AP and F2 increased fecal weight. AP, F1 and F2 increased cecal weight. F1 lowered cecal pH. Plasma triglyceride was suppressed by AP, F1 and F3. Although F1, F2 and F3 increased cecal bifidobacteria, AP did not change bifidobacteria and decreased lactobacilli.