Effects of 2 lipid emulsions (LCT versus MCT/LCT) on the fatty acid composition of plasma phospholipid: A double-blind randomized trial

Background: Fatty acids from the diet or from IV fat emulsions are incorporated into the plasma and cell membrane phospholipids and act as substrates in the synthesis of eicosanoids. This study reports the effect of 2 parenteral lipid emulsions in plasma phospholipids fatty acids. Methods: A total of 83 patients aged 18 to 75 years were randomized to receive long-chain triglycerides (LCT) or 50/50 mix of long- and medium-chain triglyceride emulsion (LCT/MCT). Blood samples were collected at baseline and at weekly intervals for 28 days. Plasma phospholipid fatty acids were measured by gas chromatography. Results: Patients receiving LCT versus MCT/LCT emulsion have an increase in 18:2n6 and a decrease in 20:4n6 and 22:4n6 after 7, 14, and 21 days of treatment with parenteral nutrition. Phospholipid fatty acids at 15 days of treatment with parenteral nutrition with LCT versus MCT/LCT for 18:2n6 were 17.30% versus 22,90% (p <.05), for 20:4n6 10.44% versus 8.38% (p <.05), and for 22:4n6 0.51% versus 0.40% (p <.05). The 20:4n6 percentage inversely correlated with the percentage of 18:2n6 on days 7, 14, and 21: regression coefficients: -7.40 (p <.001), -7.39 (p <.001), and 5.70 (p <.001), respectively. Conclusions: Parenteral lipid emulsions modify fatty acid profiles in plasma phospholipids. MCT/LCT emulsions produce in phospholipids a fatty-acid profile that is closer to normality than that achieved with LCT emulsions. These changes in phospholipid fatty acids are suggestive of an inhibition of A-5-desaturase in patients who received LCT emulsions.