OAT BETA-GLUCAN INCREASES BILE-ACID EXCRETION AND A FIBER-RICH BARLEYFRACTION INCREASES CHOLESTEROL EXCRETION IN ILEOSTOMY SUBJECTS

The purpose of this study was to investigate whether oat beta-glucan i s responsible for the increased bile acid excretion previously observe d with oat-fiber diets. The excretion patterns in ileostomy subjects g iven diets containing oat-bran bread with and without added beta-gluca nase, a beta-glucan-degrading enzyme, were compared. The effect of a b eta-glucan-rich barley fraction on sterol excretion was also investiga ted. Nine ileostomy subjects were served four diets in random order, e ach diet for 2 consecutive days. Four different kinds of bread, mainly made from oat bran (OB diet, 12.5 g beta-glucanid), oat bran with bet a-glucanase (OBE diet, 3.8 g beta-glucan/d), barley (B diet, 13.0 g be ta-glucan/d), or wheat flour (W diet, 1.2 g beta-glucan/d) were added to a basal diet. The 24-h excretion of bile acids was 53% higher in th e OB diet period than in the OBE diet period (P < 0.05) and also was s ignificantly higher than in the B and W diet periods (P < 0.05). Media n (range) bile acid excretion was 851 (232-1550), 463 (123-1414), 755 (133-1187), and 606 (101-980) mg/d in the OB, OBE, B, and W diet perio ds, respectively. The excretion of cholesterol was significantly highe r in the B diet period than in the OBE and W diet periods (P < 0.05), but the mechanism behind this effect of barley fiber is unknown. In oa t bran, however, beta-glucan mediates an increase in bile acid excreti on, which most probably explains the effect of oat fiber in lowering s erum lipids.