Randomized, controlled, crossover trial of oat bran in hypercholesterolemic subjects

Despite animal and metabolic ward studies that support the benefit of oat bran as a useful dietary supplement for the lowering of cholesterol, there have been few controlled studies on free-living subjects that have convincingly demonstrated this benefit.

This is a report of a randomized, controlled, blinded clinical trial with a crossover design using oat bran (28 g [1 oz] twice daily) vs wheat cereal as a supplement to a fat-modified diet for the reduction of total cholesterol and low-density lipoprotein (LDL) cholesterol. The study included male and female subjects aged 20 to 70 years, with baseline LDL cholesterol in the 50th to 95th percentile. All subjects were instructed in the American Heart Association Step I (AHA-I) diet, and eating behavior was monitored using 4-day food records during each study period.

Eighty-two percent (n = 145) of the total number of subjects who were randomized to treatment groups completed the study. Blood lipid studies demonstrated significantly greater reductions in total cholesterol (average -2.2%) and LDL cholesterol (average -3.9%) in the oat-bran groups than in the wheat-cereal groups (average total cholesterol +3.3%, average LDL cholesterol +4.0%) or in the diet alone group (total cholesterol +6.0%; LDL cholesterol +6.4%). All groups did comparably well at adhering to the AHA-I diet; however, dietary factors alone, when analyzed by the Keys equations, could not explain the group differences in lipid change.

The addition of oat bran (28 g [1 oz] twice daily) to the AHA-I diet provided significant added benefit in lowering total cholesterol and LDL cholesterol in most hypercholesterolemic subjects. Analysis for factors that predict LDL cholesterol response to oat bran revealed a significant age-by-sex interaction (P less than .001). Women under the age of 50 years, as a group, showed essentially no increased benefit from the addition of oat bran to their diet. Cholesterol levels in older women appear to be significantly more responsive to a modified diet containing oat bran than those of younger women.