Plasma fatty acid profile in advanced cirrhosis: unsaturation deficit of lipid fractions. Fatty acid (FA) profile of plasma total lipids, phospholipids (PL), cholesteryl esters (CE), and triglycerides (TG) were measured in 101 patients with advanced liver cirrhosis and in 44 age- and sex-matched healthy controls. Plasma levels of lipidic phosphorus, esterified cholesterol, and TG also were measured, and the unsaturation index (UI) was calculated for each fraction. Total plasma concentrations of saturated FA, linoleate, and polyunsaturated FA (PUFA) were lower in cirrhotics than in controls. This profile was also found in plasma levels of PL- and CE-associated FA. No detectable amounts of C20:3n9 were found in cirrhotic patients. Percent FA distribution of lipid fractions showed a lower percentage of linoleate and PUFA and a higher relative amount of saturated and monoenoic FA in cirrhotics than in controls. As a consequence, the UI of PL and CE was diminished in liver cirrhosis. Linoleate and PUFA deficiency was more marked in CE than in PL, as shown by the number of patients with values below the 5th percentile of the control group, suggesting an attempt to maintain the unsaturation of PL as the most important component of cell membranes. Hepatic failure, poor essential FA intake, and malnutrition are some of the possible etiologic factors for PUFA deficiency in cirrhosis. Their relative contribution to plasma FA abnormalities, as well as the clinical and pathophysiological consequences of PUFA deficit in cirrhotic patients, requires further investigation. 