Plasma cholesterol-lowering effect on rats of dietary fiber extracted fromimmature plants

Crude dietary fiber samples were prepared from beet, cabbage, Japanese radi sh, onion and mung bean sprouts (BF, CF, RF, OF and MF, respectively), Thes e samples contained total dietary fiber at the levels of 814, 699, 760, 693 and 666 g/kg, respectively. To examine the effect of these dietary fiber s ources on the plasma cholesterol concentration, male Sprague-Dawley rats we re fed on a fiber-free (FF) diet or on an FF diet supplemented with 5% or 1 0% dietary fiber. Dietary fiber extracted from vegetables, wood cellulose ( CL), pectin (PE) and guar gum (GG) were used as the fiber sources. Compared with the rats fed on the FF diet, a significant reduction in the plasma ch olesterol concentration was observed in the rats fed on BF, CF, RF, MF, PE or GG after a 21-d feeding period. Cecal acetate, n-butyrate and total shor t-chain fatty acids were significantly higher in the rats fed on these diet ary fibers, except for CF, than in those fed on the FF diet. A negative cor relation was apparent between the total dietary fiber content, hemicellulos e content and pectin content of each dietary fiber source and the plasma ch olesterol concentration. These results suggest that some vegetable fibers e xert a plasma cholesterol-lowering effect through cecal fermentation of the se fibers.