Dietary stearic acid and thromboxane-prostacyclin biosynthesis in normal human subjects

Ten male subjects were fed a diet rich in stearic acid while they were confined to a metabolic ward. There were three study periods: a 20-d baseline period followed by two 40-d intervention periods. The baseline diet contained 4.4% of energy from stearic acid; one intervention diet was high in stearic acid (7.3% of energy) and the other intervention diet was low in stearic acid (1.6% of energy). The energy contribution of protein, carbohydrate, and fat (16%, 54%, and 30%, respectively) was identical for the two diets. The fat content was distributed equally among saturated, monounsaturated, and polyunsaturated fatty acids. Urinary excretions of thromboxane B2, 2,3-dinor-thromboxane B2, 6-oxo-prostaglandin F1a, and 2,3-dinor-6-oxo-prostaglandin F1awere not significantly different during the two different intervention periods. This suggests that changes in dietary stearic acid do not affect in vivo thromboxane A2or prostacyclin.