Effect of palm oil, margarine, butter, and sunflower oil on the serum lipids and lipoproteins of normocholesterolemic middle-aged men

Abstract

Twenty-nine healthy middle-aged men participated in a Latin square-designed study containing six dietary fats: butter; crude palm oil; hard margarine; refined palm oil; 80% refined palm oil + 20% sunflower oil blend; and sunflower oil. Each diet period was 6 weeks in duration followed by 6 weeks of habitual diet. Test fats were consumed in ice cream, milk, cookies, and as spreads and represented 50% of the total fat energy (38%) on all diets. Serum lipid responses to the high level of test fats in the diets were small relative to habitual diet values. Large changes in quantity and type of fatty acids consumed daily were not reflected in the fatty acid composition of the total serum lipids. Butter did not elevate total serum cholesterol or low density lipoprotein (LDL) cholesterol relative to habitual diet levels, but these values were significantly higher than sunflower oil-diet and palm oil-diet values. The sunflower oil diet produced the most dramatic changes: total serum cholesterol was reduced significantly relative to all diets except margarine, and apolipoprotein B values were the lowest of any diet. Unfortunately, the desirable high density lipoprotein (HDL) cholesterol and apolipoprotein A1 were also reduced on the sunflower oil diet. Diets containing either crude or refined palm oil did not elevate total serum cholesterol relative to habitual diet values or LDL cholesterol or apolipoprotein levels relative to any diet. Unexpectedly, the refined palm oil diet HDL-cholesterol and apolipoprotein A1 levels were the highest of all diets and significantly higher than sunflower oil diet values. The hard margarine diet, containing 26% trans fatty acids, reduced apolipoprotein B values relative to habitual diet levels, but HDL cholesterol was reduced significantly relative to the refined palm oil diet values. Comparison of the diet's fatty acid compositions suggests the decrease in the HDL cholesterol on the hard margarine diet is attributable to the trans fatty acids. The data indicate that the trans fatty acids, produced during the partial hydrogenation of fats and oils, are not neutral and adversely affect serum lipid profile.