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OBJECTIVE: To examine, in free-living adults eating self-selected diets, the effects on plasma cholesterol of substituting saturated fat rich foods with either n-6 polyunsaturated or monounsaturated fat rich foods while at the same time adhering to a total fat intake of 30-33% of dietary energy. DESIGN: Two randomised crossover trials. SETTING: General community. SUBJECTS: Volunteer sample of healthy free-living nutrition students at the University of Otago. Trial I, n=29; and trial II, n=42. INTERVENTIONS: In trials I and II participants were asked to follow for 2(1/2) weeks a diet high in saturated fat yet with a total fat content that conformed to nutrition recommendations (30-33% energy). During the 2(1/2) week comparison diet, saturated fat rich foods were replaced with foods rich in n-6 polyunsaturated fats (trial I) whereas in trial II the replacement foods were rich in monounsaturated fats. Participants were asked to maintain a total fat intake of 30-33% of energy on all diets. MAIN OUTCOME MEASURES: Energy and nutrient intakes, plasma triglyceride fatty acids, and plasma cholesterol. RESULTS: When replacing saturated fat with either n-6 polyunsaturated fat or monounsaturated fat, total fat intakes decreased by 2.9% energy and 5.1% energy, respectively. Replacing saturated fat with n-6 polyunsaturated fat (trial I) lowered plasma total cholesterol by 19% [from 4.87 (0.88) to 3.94 (0.92) mmol/l, mean (s.d.)], low density lipoprotein cholesterol by 22% [from 2.87 (0.75) to 2.24 (0.67) mmol/l], and high density lipoprotein cholesterol by 14% [from 1.39 (0.36) to 1.19 (0.34) mmol/l], whereas replacing saturated fat with monounsaturated fat (trial II) decreased total cholesterol by 12%, low density lipoprotein cholesterol by 15%, and high density lipoprotein cholesterol by 4%, respectively. The change in the ratio of total to high density lipoprotein cholesterol was similar during trial I and trial II. CONCLUSIONS: Young adults are very responsive to dietary-induced changes in plasma cholesterol even when an isocaloric replacement of saturated fat with n-6 polyunsaturated or monounsaturated fat is not achieved. Replacing saturated fat with either n-6 polyunsaturated or monounsaturated fat is equally efficacious at reducing the total to high density lipoprotein cholesterol ratio. SPONSORSHIP: University of Otago, Meadow Lea Ltd.

Original publication

DOI

10.1038/sj.ejcn.1601234

Type

Journal article

Journal

Eur J Clin Nutr

Publication Date

10/2001

Volume

55

Pages

908 - 915

Keywords

Adult, Cholesterol, Cholesterol, HDL, Cholesterol, LDL, Cross-Over Studies, Dietary Fats, Dietary Fats, Unsaturated, Energy Intake, Fatty Acids, Monounsaturated, Fatty Acids, Omega-6, Fatty Acids, Unsaturated, Female, Humans, Male, Treatment Outcome, Triglycerides