Ea. Trautwein et al., CHOLESTEROL-LOWERING AND GALLSTONE-PREVENTING ACTION OF CHITOSANS WITH DIFFERENT DEGREES OF DEACETYLATION IN HAMSTERS FED CHOLESTEROL-RICH DIETS, Nutrition research, 17(6), 1997, pp. 1053-1065
The lipid-lowering potential of chitin and chitosan (CHI) and their pr
otective effect against cholesterol gallstone formation was investigat
ed by feeding male Golden Syrian hamsters gallstone-inducing diets. Si
nce the physicochemical properties like degree of deacetylation or vis
cosity are thought to be involved in the hypocholesterolemic action of
CHI, two varieties of CHI, a 92% and a 79% deacetylated CHI (CHI92 an
d CHI79) were tested. Hamsters were fed semipurified, gallstone-induci
ng diets containing 5% fat, 0.4% cholesterol and 10% cellulose with or
without supplements of chitin (8%) or the two CHIs (8% and 4%). After
5 weeks, 8% CHI79 significantly reduced plasma lipids (total choleste
rol (TC): 4.5 +/- 0.7 vs 10.1 +/- 3.9 mmol/L and triglycerides (TG): 2
.9 +/- 1.5 vs 7.3 +/- 3.6 mmol/L compared to the control diet), wherea
s 8% CHI92 produced only a minor hypocholesterolemic effect (-10%). Fe
eding 8% CHI92 or CHI79 caused a significant reduction in food intake,
body weight gain and liver weight. The adverse effect on food intake
and growth was lessened by feeding 4% CHI92 or CHI79, but the differen
ces were still significant for CHI92. The supplementation with 4% of b
oth CHIs resulted in a significant lowering of plasma cholesterol with
a reduction in TC of 38% with CHI92 and 32% with CHI79 compared to th
e control diet. Hepatic cholesterol was significantly decreased with 8
% CHI79, whereas 8% CHI92 caused only a negligible reduction. The 4% s
upplement of CHI92 did not alter cholesterol accumulation in the Ever,
but hepatic total cholesterol was significantly increased with 4% CHI
79. While the 8% supplements of both CHIs completely inhibited cholest
erol gallstone formation, 4% CHI92 or CHI79 added to the diet had no p
reventive effect and a 90% incidence of cholesterol gallstones was obs
erved. 8% chitin produced no apparent effects on plasma, hepatic and b
iliary lipids. Whereas 8% CHI79 significantly increased the cholate :
chenodeoxycholate ratio of gallbladder bile by decreasing particularly
taurochenodeoxycholate, 8% CHI92 had no distinct impact on bile acid
composition. The 4% supplements of CHI92 or CHI79 did not alter biliar
y lipids and bile acid distribution. The dried fecal weight was double
d by feeding 8% and 4% of CHI92 or CHI79 compared to the control diet.
Whereas the daily excretion of neutral sterols was significantly expa
nded with the 8% supplements of CHI92 and CHI 79, only CHI79 caused al
so a 1.9-fold increase in the daily bite acid excretion. The supplemen
tation with 4% of CHI92 or CHI79 did not significantly change fecal ex
cretion of bile acids or neutral sterols although daily excretion of n
eutral sterols was increased by 20%. These data demonstrate that in ha
msters feeding CHI is associated with a reduced food intake and that t
he cholesterol-lowering effect seems mainly related to an increase in
the fecal excretion of neutral sterols. (C) 1997 Elsevier Science Inc.