Background: It is well-known that the saturated fatty acid stearic acid (C18:0) lowers LDL-cholesterol and HDL-cholesterol concentrations as compared with palmitic acid (C16:0). As related to CHD risk, the decrease in LDL-cholesterol is beneficial, while the decrease in HDL-cholesterol is controversial. Recent evidence suggests that not increased HDL-cholesterol concentrations, but the ability of the HDL particles to perform cholesterol efflux from macrophages (cholesterol efflux capacity; CEC) may protect against CHD risk. Therefore, our primary objective was to examine the effects of palmitic acid versus stearic acid on CEC of the HDL fraction during the fasted state. Secondary objectives were effects on fasting lipids, (apo)lipoproteins, and cholesteryl ester transfer protein (CETP). 

Study design and population: This study was a double-blind, randomized, crossover study with two four-week isocaloric intervention periods, during which subjects received products enriched with palmitic acid or stearic acid. Difference between palmitic acid and stearic acid intakes were 6% of total energy. Thirty-four healthy men and women (61.5±5.7 years, BMI: 25.4±2.5 kg/m2) completed the study.

Results: CEC was not significantly different between the diets. Compared with palmitic acid, stearic acid lowered concentrations of total-cholesterol, LDL-cholesterol, HDL-cholesterol, and apolipoprotein-A1. No significant differences were observed in apolipoprotein-B100 and triacylglycerol concentrations. CETP mass was higher on the stearic acid diet. 

Conclusion: Although concentrations of HDL-cholesterol and apolipoprotein-A1 were lower on the stearic acid diet, CEC was not significantly different. CETP may be involved in the observed decrease in HDL-cholesterol. Stearic acid lowered total- and LDL-cholesterol, without lowering the total number of apoB100-containing lipoproteins.

This study was funded by Unilever R&D Vlaardingen (before divesting its spreads business and since July 2, 2018 operating under the name Upfield™).

05 - THE SATURATED FATTY ACIDS PALMITIC ACID AND STEARIC ACID DO NOT DIFFERENTLY AFFECT CHOLESTEROL EFFLUX CAPACITY: RESULTS OF A HUMAN DIETARY INTERVENTION TRIAL