Oat bran stimulates bile acid synthesis within 8 h as measured by 7 α-hydroxy-4-cholesten-3-one

Abstract

Background: Oat bran contains soluble fibers, such as β-glucan, that increase bile acid excretion and thus decrease serum cholesterol. Bile acid synthesis correlates with serum concentrations of the metabolite 7α-hydroxy-4-cholesten-3-one (α-HC). Objective: The objective was to investigate whether consumption of β-glucan from oat bran increases bile acid synthesis, as measured by the serum α-HC concentration, within hours after consumption in response to the loss of bile acids from the liver. Design: In a randomized, single-blind, wheat bran - controlled study with crossover design, 8 subjects were served a controlled diet during 2 periods of 3 d each, with an 11-d washout between the periods. Breakfast included either 75 g extruded oat bran, of which 11 g was β-glucan, or 75 g wheat bran, of which 1 g was β-glucan. α-HC was measured by HPLC on each day at 0, 12, and 24 h after breakfast and also at 8 h after breakfast on the first day. Results: After 8 and 12 h of the oat bran diet period, the serum α-HC concentration was 84% (P = 0.012) and 92% (P = 0.017) higher, respectively, than that before breakfast. Serum concentrations returned to the baseline value after 24 h. Wheat bran did not influence serum α-HC concentrations. Conclusions: Consumption of β-glucan from oat bran nearly doubled the serum α-HC concentration within 8 h, indicating increased bile acid synthesis. α-HC in serum could be used as a marker of increased bile acid excretion induced by the diet.