Effects of soluble and insoluble fiber preparations isolated from oat, barley, and wheat on liver cholesterol accumulation in cholesterol-fed rats.

Effects of soluble and insoluble fiber preparations isolated from defatted oat, barley, and wheat on liver cholesterol accumulation were examined in cholesterol-fed rats. The soluble and insoluble fiber preparations were isolated by a modification of the procedure of Asp et al. Male Sprague-Dawley rats, aged 5 weeks, were fed a control diet containing 5% cellulose or diets containing soluble and insoluble fiber preparations for 9 days. Soluble fiber preparations from oat, barley, and wheat were added to diets corresponding to 1.9, 2.8, and 0.6% fiber, respectively. Insoluble fiber preparations from oat, barley, and wheat were added to diets corresponding to 3.1, 2.2, and 4.4% fiber, respectively. All of the soluble fiber preparations suppressed liver cholesterol accumulation, but they did not suppress the elevation of plasma cholesterol concentrations. A significant inverse relationship between the quantity of ingested soluble fiber and liver cholesterol accumulation was observed; n = 28, r = -0.943, p < 0.0001. None of the insoluble fiber preparations had any significant effect on liver and plasma cholesterol concentrations. These results indicate that the water-soluble fractions of oat, barley, and wheat are the active components that suppressed liver cholesterol accumulation, and that these effects are related to the quantity of ingested soluble fiber.