Abstract
This study addresses the important issue of whether oat bran has an effect on serum cholesterol levels, independent of and additive to, that of a low-fat diet. Patients were maintained on the American Heart Association Step 1 diet for at least 8 weeks. This allowed stability to the low-fat, low-cholesterol diet. Two hundred eleven patients entered the initial 8-week dietary instruction/ stabilization phase. After the initial 8-week period, two qualifying serum lipid profiles were determined within 1 week. One hundred fifty-six men and women volunteers, ages 30 to 65 years, with mild to moderate hypercholesterolemia, as defined by LDL-cholesterol levels greater than 4.14 mmol/L (160 mg/dL) or between 3.37 and 4.14 mmol/L (130 and 160 mg/dL), qualified for entering the study. Patients were randomized in a parallel fashion into seven equal groups. Three groups received oat bran in either 1-, 2-, or 3-oz doses per day; three groups received oatmeal in either 1-, 2-, and 3-oz doses per day; and one control group received 1 oz of dry farina per day. All groups were followed for 6 weeks on the dietary supplements, with serum lipid measurements carried out after 3 and 6 weeks. After this, supplements were discontinued and serum lipid profiles were determined after a 6-week "washout" period.
Of the 156 randomized patients, 148 completed the 12-week study (dropout rate: 5%). The data from eight patients who completed the study were not analyzed because of less than 80% compliance. Therefore, 140 patients were used for data analysis. After 6 weeks of treatment, there were significant decreases in total and low-density lipoprotein cholesterol levels in all groups receiving oat bran or oatmeal, when compared with the farina (control) group. A significant dose-response relationship was observed between total β-glucan intake, whether from oat bran or oatmeal, and change in low-density lipoprotein cholesterol level from baseline. The 2-oz oat bran and 3-oz oatmeal supplements seemed to produce maximal effect, with the 3-oz oat bran supplementation resulting in no additional cholesterol lowering. There was no change in cholesterol levels in the control group. During the 6 weeks after discontinuation of the supplement, cholesterol levels returned to their prestudy levels in all patient groups. Nutrient analysis showed no difference in dietary fat content among the treatment groups. The authors thus concluded that the higher β-glucan content of oat bran most likely resulted in the significantly greater reduction in serum low-density lipoprotein cholesterol levels.
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