Medium- and long-chain triacylglycerols in postoperative patients: structured lipids versus a physical mixture

Forty patients, scheduled for abdominal surgery, were randomized to receive postoperatively either a structured or a physical mixture of long-chain triacylglycerols/medium-chain triacylglycerols (LCT/MCT) emulsions to assess the tolerance and the effectiveness of the structured triacylglycerol emulsion. Total parenteral nutrition started the day after surgery and covered 100% of measured energy expenditure with nitrogen (0.2 g N.kg-1.d-1) and non-protein calories: glucose (50%) and lipids (50%). Blood samples for liver function tests, albumin, transthyretin, and triacylglycerols were checked at 0800 h on the day before surgery and on day 1, day 3, and day 6 after surgery. Urine samples were taken each day from day 1 to day 7 for 3-methylhistidine (3 Me His) and total nitrogen measurements. Aspartate transaminase (ASAT), alanine transaminase (ALAT), and triacylglycerol plasma levels in routine clinical biochemistry increased significantly in the physical mixture group. Nitrogen balance and 3 Me His excretion were not significantly different between groups. Structured triacylglycerol (STG) lipid emulsions are as efficacious as the physical mixture on nitrogen balance in postoperative patients. They could have some advantages: no disturbances were found to occur in liver function tests or plasma triacylglycerol levels.