RICE BRAN OIL CONSUMPTION AND PLASMA-LIPID LEVELS IN MODERATELY HYPERCHOLESTEROLEMIC HUMANS

The effect of rice bran oil, an oil not commonly consumed in the United States, on plasma lipid and apolipoprotein concentrations was studied within the context of a National Cholesterol Education Panel (NCEP) Step 2 diet and compared with the effects of canola, com, and olive oils. The study subjects were 15 middle-aged and elderly subjects (8 postmenopausal women and 7 men; age range, 44 to 78 years) with elevated low-density lipoprotein (LDL) cholesterol (C) concentrations (range, 133 to 219 mg/dL). Diets enriched in each of the test oils were consumed by each subject for 32-day periods in a double-blind fashion and were ordered in a Latin square design. All food and drink were provided by the metabolic research unit. Diet components were identical (17% of calories as protein, 53% as carbohydrate, 30% as fat [<7% as saturated fat], and 80 mg cholesterol/1000 kcal) except that two thirds of the fat in each diet was contributed by rice bran, canola, com, or olive oil. Mean+/-SD plasma total cholesterol concentrations were 192+/-19, 194+/-20, 194+/-19, and 205+/-19 mg/dL, and LDL-C concentrations were 109+/-30, 109+/-26, 108+/-31, and 112+/-29 mg/dL after consumption of the rice bran, canola, corn, and olive oil-enriched diets, respectively. Plasma cholesterol and LDL-C concentrations were similar and statistically indistinguishable when the subjects consumed the rice bran, canola, and com oil-enriched diets and lower than when they consumed the olive oil-enriched diet. Concentrations of very-low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglyceride, LDL apolipoprotein (apo) B, apoA-I, and lipoprotein(a) and the total cholesterol to high-density lipoprotein cholesterol and apoB to apoA-I ratios were not significantly different during consumption of the different vegetable oil-enriched diets. Differences observed in the fasting state were maintained in the postprandial state. These data suggest that in middle-aged and elderly subjects with moderately elevated levels of LDL-C, consumption of diets enriched in rice bran oil results in plasma lipid and apolipoprotein concentrations and predictive ratios of cardiovascular risk that are similar to those of more commonly used vegetable oils in the United States.