| J Nutr 2000 Nov;130(11):2753-9
- Cholesterol reduction
by glucomannan and chitosan is mediated by changes in cholesterol
absorption and bile acid and fat excretion in rats.
Gallaher CM, Munion J, Hesslink R Jr, Wise J, Gallaher DD.
Department of Food Science and Nutrition, University of Minnesota,
St. Paul, MN, USA.
Glucomannan, a viscous polysaccharide, and chitosan, a derivative
of chitin, have both been demonstrated to lower cholesterol
in animals. However, the mechanism of cholesterol lowering has
not been established for either material. This study was conducted
to determine the effect of glucomannan (G), chitosan (CH), or
an equal mixture of the two (G + CH) on cholesterol absorption
and fat and bile acid excretion. Rats were fed a modified AIN-93G
diet for 18 d containing 0.125 g/100 g cholesterol and initially
10 g/100 g of the test materials or cellulose (C) as the control.
However, the concentration of test materials and cellulose was
reduced to 7.5 g/100 g after 1 wk due to lower weight gain compared
with controls. Total liver cholesterol was significantly reduced
in G, CH and G + CH groups compared with the C group. The intestinal
contents supernatant viscosity of the C and the CH groups was
negligible, whereas both G and G + CH produced high viscosities.
Cholesterol absorption, measured by the fecal isotope ratio
method, was significantly reduced from 37.5% in the C group
to 20.2% in G, 18.2% in G + CH and 9.4% in CH. Daily fecal fat
excretion did not differ between the C and G groups, but was
significantly greater in G + CH and CH compared with the C and
G groups. Daily fecal bile acid excretion was significantly
greater in the CH and G + CH groups compared with the C and
G groups. These results suggest that G lowered liver cholesterol
by a viscosity-mediated interference of cholesterol absorption.
In contrast, CH appears to lower cholesterol through a different