New Research on Unsaturated Fats Using NMR LipoProfile Test

Small differences in the effects of stearic acid, oleic acid, and linoleic acid on the serum lipoprotein profile of humans1–3

Myriam A Thijssen and Ronald P Mensink

ABSTRACT

Background: Studies have suggested that oleic and stearic acids, as well as oleic and linoleic acids, have comparable effects on the serum lipoprotein profile. If so, then substituting these three 18-carbon fatty
acids for each other would result in similar effects on the serum lipoprotein profile.

Objective: The aim of this study was to compare simultaneously the effects of stearic, oleic, and linoleic acids on the serum lipoprotein profile of healthy subjects.

Design: Forty-five subjects (27 women and 18 men) consumed in random order 3 experimental diets, each for 5 wk. The diets provided 38% of energy from fat, of which 60% was supplied by the experimental
fats. The dietary compositions of the diets were the same, except for 7% of energy, which was provided by stearic, oleic, or linoleic acid. At the end of each intervention period, serum lipid and lipoprotein concentrations were measured. In addition, LDL, HDL, and VLDL particle sizes and particle concentrations of lipoprotein subclasses were analyzed by nuclear magnetic resonance spectroscopy.

Results: No significant diet-induced changes in serum lipids and lipoproteins were found. Mean (
SD) serum LDL-cholesterol concentrations were 3.79
0.91, 3.71
0.79, and 3.65
0.91 mmol/L with the high–stearic acid, high– oleic acid, and high–linoleic acid diets, respectively (P 0.137 for diet effects). Mean (
SD) HDLcholesterol concentrations were 1.45
0.43, 1.46
0.45, and 1.46
0.44 mmol/L (P 0.866). LDL, HDL, and VLDL particle sizes and lipoprotein subclass distributions also did not differ significantly
between the 3 diets.

Conclusions: With realistic intakes of stearic, oleic, and linoleic acids, differences between their effects on the serum lipoprotein profile are small. Am J Clin Nutr 2005;82:510–6.

KEY WORDS Stearic acid, oleic acid, linoleic acid, total cholesterol, LDL cholesterol, HDL cholesterol, lipoprotein profile, humans

INTRODUCTION
It is well known that the various fatty acids in the diet exert different effects on serum lipid and lipoprotein concentrations. Saturated fatty acids are thought to increase cardiovascular disease risk because they elevate serum total and LDL-cholesterol concentrations relative to monounsaturated and polyunsaturated
fatty acids. These effects have been quantified by earlier wellcontrolled dietary studies (1, 2). Relative to an isoenergetic amount of carbohydrates, a mixture of saturated fatty acids elevated serum total cholesterol concentrations, monounsaturated fatty acids had comparable effects, and polyunsaturated fatty acids were hypocholesterolemic. In contrast with the other saturated fatty acids, stearic acid—a saturated fatty acid with 18 carbon atoms—had no effects on serum total cholesterol concentrations (1, 2). These earlier studies, however, did not examine the effects of fatty acids on specific lipoproteins, which is important because of the opposing effects of LDL and HDL cholesterol on cardiovascular disease risk. More recently, several studies have compared the effects of stearic acid on lipid and lipoprotein concentrations with those of unsaturated fatty acids. When stearic acid was substituted for oleic acid, effects on serum LDL- and HDL-cholesterol concentrations did not differ (3). Also, with realistic intakes of linoleic acid (13% of energy), oleic and linoleic acids had similar effects on the serum lipoprotein profile (4, 5). If these findings are true (3-5), then the consequence is that the effects of stearic, oleic, and linoleic acids on serum lipid and lipoprotein concentrations would be comparable. To examine this hypothesis, we compared the effects of diets enriched in these three 18-carbon fatty acids on serum concentrations of triacylglycerol and total, LDL, and HDL cholesterol in a controlled crossover study in healthy subjects. In addition, we investigated the effects of these diets on LDL, HDL, andVLDLparticle sizes and on the subclass distributions of these lipoprotein particles by nuclear magnetic resonance (NMR) spectroscopy.

To purchase a NMR LipoProfile test simply order online at LabSafe at http://www.lab-safe.com/lab-tests/test/532/ or visit our website at http://www.labsafe.com/

For more information, or to speak with a member of our professional Medical Staff, call LabSafe toll free at 1-888-333-LABS.