Abstract
Little known about the physiological and industrial applications of Rhodotorula mannan with repeated β-1, 3 and 1, 4 bonds, which is excreted from the cells of yeast and is different from Konjak mannan in its chemical structure. This study was carried out to examine the effects of mannan on serum and liver lipid concentrations in rats fed cholesterol-free and -enriched diets. The serum triacylglycerol concentration was lower in rats fed the diet supplemented with Rhodotorula mannan than in those fed the diet without Rhodotorula mannan, for both cholesterol-free and -enriched diets. For rats fed the cholesterol-enriched diet, the concentration of serum total cholesterol showed a tendency to become lower and the atherogenic index was significantly lower in the rats fed Rhodotorula mannan than in the control rats. The atherogenic index showed a significant interaction between cholesterol and Rhodotorula mannan, indicating that Rhodotorula mannan suppresses an increase in the atherogenic index induced by dietary cholesterol. Addition of Rhodotorula mannan to the cholesterol-enriched diet also lowered the concentration of total liver lipids, and interaction was observed between cholesterol and Rhodotorula mannan. Because ingestion of Rhodotorula mannan did not increase fecal excretion of bile acid or neutral steroids in the cholesterol-fed rats, the effect of Rhodotorula mannan in lowering the serum cholesterol level may be mediated by a mechanism other than enhancement of steroid excretion into the feces.
