We have shown previously that cecal fermentation plays an essential part in the hypocholesterolemic activity of beet fiber (BF) in rats. In the present study, we compared such activities of 10% plant cellulose (CL), 10% BF, 5% pectin (PE), 5% guar gum (GG), 5% konjac mannan (KM) and 5% arabinogalactan (AG) in rats fed a cholesterol-free diet (FF diet) for 43 days. Rats fed BF, GG or KM showed significantly lower plasma cholesterol concentrations, whereas PE showed only a slight effect. There was a significant negative correlation between plasma cholesterol concentration and the cecal pool size of total short-chain fatty acids or propionate, but not cecal acetate or n-butyrate. In vitro fermentation of 1g of GG by rat cecal bacteria produced 6.2 mmol of acetate, 1.2 mmol of propionate and 0.8 mmol of n-butyrate during a 12-h incubation. Cecal infusion of the products of the GG-fermentation (3 times/day) did not cause any reduction of the plasma cholesterol concentration in rats fed the FF diet.