Oat bran increases serum acetate of hypercholesterolemic men.

Mechanisms for the hypocholesterolemic effects of oat bran remain unclear. Soluble fibers such as oat bran are fermented in the colon to short-chain fatty acids (SCFAs), which may enter the portal vein and attenuate hepatic cholesterol synthesis. To compare effects of oat bran and wheat bran on serum SCFA concentrations, 20 hypercholesterolemic men entered a metabolic ward and received control diets for 1 wk followed by oat-bran or wheat-bran diets for 3 wk. Oat bran decreased serum cholesterol 12.8% (P less than 0.001) whereas wheat bran had no effect. Peripheral serum SCFA concentrations were measured seven times over 14 h at the end of each diet. Serum acetate values from 1200 to 2200 were significantly higher in subjects fed oat-bran vs wheat-bran diets. Peak and incremental peak acetate values were also significantly higher than control values in subjects fed oat bran but not in subjects fed wheat bran. SCFA responses may contribute to the hypocholesterolemic effects of oat bran.

Metabolic effects of high-carbohydrate, high-fiber diets for insulin-dependent diabetic individuals.

The metabolic effects of high-carbohydrate (70%), high-fiber (70 g) (HCHF) and low-carbohydrate (39%), low-fiber (10 g) (LCLF) diets were examined for 10 subjects with insulin-dependent diabetes mellitus (IDDM). After a 1-wk control period subjects on a metabolic ward were randomly allocated to HCHF or LCLF diets for 4 wk. After a 6-wk washout period subjects re-entered the metabolic ward for 4 wk on the alternate diet. Artificial-pancreas studies were performed on each diet for measurement of insulin requirements. Compared with the LCLF diet, the HCHF diet reduced basal insulin requirements (P less than 0.025), increased carbohydrate disposed of per unit insulin (P less than 0.0008), and lowered total (P less than 0.0004) and high-density-lipoprotein cholesterol (P less than 0.0013). Glycemic control and other lipid fractions did not differ significantly. These results suggest that in IDDM patients, HCHF diets enhance peripheral glucose disposal, decrease basal insulin requirements, and lower total cholesterol without altering glycemic control or triglycerides.

Lipid responses of hypercholesterolemic men to oat-bran and wheat-bran intake.

The hypocholesterolemic effects of oat bran (OB) have been recently challenged. To carefully document the hypocholesterolemic effects of OB, 20 hypercholesterolemic men admitted to a metabolic ward were randomly allocated to either OB or wheat bran (WB) for 21 d after a 7-d control-diet period. Control and treatment diets were designed to be identical in energy content and nutrients, differing only in the amount of soluble fiber. After 21 d, OB significantly decreased total cholesterol by 12.8% (P less than 0.001), low-density-lipoprotein cholesterol by 12.1% (P less than 0.004), and apolipoprotein B-100 by 13.7% (P less than 0.001) whereas WB had no significant effect. High-density-lipoprotein cholesterol and apolipoprotein A-I did not change significantly in either group. Serum triglycerides decreased by 10% in both groups but the decrease was only significant (P less than 0.04) in WB subjects. OB but not WB significantly reduced total cholesterol and other atherogenic lipoprotein fractions independent of other dietary changes.