Similar Effects of Diets Rich in Stearic Acid or trans -Fatty Acids on Platelet Function and Endothelial Prostacyclin Production in Humans

Abstract

Abstract —The effects of stearic acid (C18:0) and trans- fatty acids ( trans- FAs) on measures of platelet function and prostacyclin (PGI 2 ) production are poorly understood in humans. In this controlled dietary study, platelet function and endothelial PGI 2 production were studied in healthy humans after they consumed diets rich in C18:0 or trans- FAs. For 5 weeks, 80 subjects consumed a baseline diet high in saturated FAs and were then switched to a diet containing 9.3% of energy as stearic acid or a diet containing 8.7 energy% as trans- FAs from hydrogenated vegetable oils for another 5 weeks. All diets contained 32.2 to 33.9 energy% fat, 14.6 to 15.8 energy% saturated plus trans- FAs, 12.2 to 12.5 energy% cis -monounsaturated, and 2.9 to 3.5 energy% polyunsaturated FAs. No significant differences between the C18:0 and trans- FA diets were found in the urinary excretion of 2,3-dinor-thromboxane B 2 or 2,3-dinor-6-keto-prostaglandin F 1α . In vitro production of thromboxane B 2 by platelets as well as urinary excretion of β-thromboglobulin were also similar after both diets. Collagen-induced in vitro aggregation was significantly enhanced after the C18:0 diet compared with the trans- FA diet ( P =.02), whereas no differences between the diets were found with ADP. The results indicate similar effects of C18:0 and trans- FA diets on platelet activation and endothelial PGI 2 production.