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, corn, 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, corn, 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 Dietary recommendations to optimize plasma lipid profiles and reduce the risk of coronary heart disease are currently focused on total fat content, the fatty acid profile, and cholesterol content of the diet.Although strong and consistent evidence has demonstrated that alterations in any one of these dietary components will alter plasma lipid levels, the data are highly variable among studies. Explanations for this variability include differences in characteristics of the study population (ie, age, sex, and baseline plasma lipids), experimental conditions, and Received October 18, 1993; revision accepted January 12, 1994. From the Lipid Metabolism Laboratory, US Department of Agriculture Human Nutrition Research Center on aging at Tufts University, Boston, Mass (A.H.L, W.C., J.LJ., J.M.O., EJ.S.); the School of Nutrition (L.M.A.) and Department of Community Medicine (L.J.G., B.R.G.), Tufts University, Medford, Mass; and the Department of Clinical Sciences, University of Lowell, Lowell, Mass (RJ.N.). Presented in part at the 64th Scientific Sessions of the American Heart Association, Anaheim, Calif, November 12, 1991, and published in abstract form (Circulation 1991;84[suppl II]:V-219). The contents of this publication do not necessarily reflect the views or policies of the US Department of Agriculture, nor does mention of trade names, commercial products, or organizations imply endorsement of the US government. Reprint requests to Dr A.H. Lichtenstein, HNRC/Tufts University, 711 Washington St, Boston, MA 02111. and statistically indistinguishable when the subjects consumed the rice bran, canola, and corn 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. (Arterioscler Thromb. 1994;14:549-556.)