Objectives: Prostacyclin is a prostanoid derived from arachidonic acid that prevents thrombosis and is thereby expected to protect against heart disease, while trans fats present in partially hydrogenated oils interfere with arachidonic acid metabolism. Therefore, the objective of the present study was to investigate how fats with different proportions of linoleic acid and trans-18:1 affect prostacyclin released by cultured endothelial cells, and to compare these proportions with those found in commercially available foods.
Design: Soybean oil and hydrogenated soybean oil (coating fat) were mixed in different proportions to yield seven fat mixtures with proportions of linoleic acid ranging from 54.1% to 5.7% and trans-18:1 acid ranging from 0.4% to 43.9%. Human endothelial cells were cultured in each of the mixtures, and their phospholipid fractions were then separated and their fatty acids were analyzed by gas chromatography. The prostacyclin released by the cells was measured using RIA kits. Margarines and processed foods were purchased from the supermarket for comparison.
Results: Our work revealed that as the percentage of trans fat was increased, the amount of prostacyclin released dose-dependently and significantly (P < 0.0001) decreased, the concentration of linoleic and arachidonic acid decreased in the membrane phospholipids while the concentration of trans 18:1 acids increased, the prostacyclin decreased by 35-98%. Supermarket margarines had levels of trans fats similar to those that suppressed prostacyclin by 35-54%. Most processed foods labeled as trans-free contained trans fats.
Conclusions: Trans fatty acids suppress prostacyclin production at levels found in commercial margarines, and processed foods labeled as trans-free could contribute to this effect if consumed in multiple servings or in addition to foods containing larger amounts of trans fats.