The effect of replacing dietary saturated fat with polyunsaturated or monounsaturated fat on plasma lipids in free-living young adults

Abstract

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 ¼ 29; and trial II, n ¼ 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.

The tumor necrosis factor-α gene -238 G>A polymorphism, dietary fat intake, obesity risk and serum lipid concentrations in black and white South African women

“…The effects of n-6 PUFAs on inflammation are contradictory and inconclusive. 43,44 The n-6 PUFAs have, however, been shown to reduce LDL-C concentrations and T-C:HDL-C ratio, although some studies have also reported a decrease in HDL-C. 43,45 In contrast, a high n-6:n-3 PUFA ratio is regarded as pro-inflammatory and has been associated with cardiovascular disease, inflammatory and autoimmune diseases. 44,[46][47][48] Notably, the intake of n-6 PUFAs (%E) and the n-6:n-3 PUFA ratio in the black women were higher than that of the white women in this study (8.3% versus 5.6%, and 26.4:1 versus 16.1:1, for black and white women, respectively) and that reported in other populations (4.0-6.0% for n-6 PUFA (%E), 43 and B15:1 for n-6:n-3 PUFA ratio 49 ).…”

Long-term walnut supplementation without dietary advice induces favorable serum lipid changes in free-living individuals

“…In previous studies, nuts were used to replace other forms of fat such as animal fat and saturated fat (Dreaon et al, 1990;Ginsberg et al, 1990;Abbey et al, 1994;Hodson et al, 2001). Some other studies such as those conducted by Tapsell et al (2004Tapsell et al ( , 2009) three dietary advice groups of type II diabetics were given daily walnuts.…”

Dietary intake of n-3, n-6 fatty acids and fish: Relationship with hostility in young adults—the CARDIA study

“…Some animal studies have shown that n-6-enriched diets result in decreased atherosclerosis (George et al, 2000) and several epidemiological studies have found that linoleic acid in the adipose tissue is inversely related to the risk of coronary heart disease (Wood et al, 1987;Tavendale et al, 1992). However, other reports indicate that n-6 fatty acids may decrease HDL concentration (Hodson et al, 2001), increase oxidative stress (Hanaoka et al, 2002) and thus potentially enhance atherosclerosis.…”