A study of human plasma lipid and lipoprotein responses to a diet high in oleic acid derived from pecans

Abstract

Pecans contain 68 gm fat per 100 gm with 66-70% as MUFA, primarily oleic acid. As a rich source of MUFA, pecans should represent a non-hyperlipidemic fat addition in isocaloric diets of equivalent SFA content. In this study hypercholesterolemic (mean ± SD serum total cholesterol, 5.76 ± 0.85 mmol/L) men and women with a pre-entry fat intake similar to an AHA Step I diet (32% fat, 10% SFA, 9.6% MUFA, 5.6% PUFA and 237 mg CHOL per day) participated in an 8 week, randomized, controlled feeding trial. Forty subjects (26 women, 14 men; mean age 55 y, range 22-71) were fed one of two diets: an AHA Step I diet (31% fat: 9.9% SFA, 9.2% MUFA, 5.5% PUFA and 225 mg CHOL) or an isocaloric but higher fat percent pecan-based diet (40% fat: 8.4% SFA, 17% MUFA, 9.9% PUFA and 203 mg CHOL). There was no significant difference in SFA intake between either treatment group; MUFA intake increased by 17.4 gm, from 19.8 to 37.2 gm per day, and PUFA intake increased 9.74 gm, from 11.5 to 21.2 gm per day. Dietary compliance was excellent as judged by changes in proportions of n-9 to n-7 fatty acids within individual plasma lipid classes. Serum lipids, density fractionated lipoproteins, apolipoproteins (Apo B100, Apo AI, Lp(a)), and acute phase proteins (CRP, SAA) were analyzed on all subjects at the end of the initial run-in period and at the end of the diet period by repeated measures analysis of variance (SAS, ProcGLM) with significance set at p<0.05. There were no significant differences between the two diet treatments with regards to any lipoprotein or inflammatory index. Both diets lowered CRP by ~33%, (pecan fed 5.18 to 3.53 mg/L; Step I fed 4.21 to 2.77 mg/L) (p>0.2). As a rich nutrient source, pecans significantly increased dietary fiber, beta-carotene, thiamin, magnesium, copper, and manganese, normalizing inadequate magnesium and copper intake. Results of this study indicate that altering the Step I diet to include 20% of daily energy intake as whole pecans can be as effective as the Step I diet in maintaining plasma lipids.