Structured Triglyceride Emulsions in Parenteral Nutrition

Abstract

Over the past 3 decades, various concepts for IV fat emulsions (IVFE) have been developed. A randomized, structured-lipid emulsion based on an old technology has recently become available. This structured-lipid emulsion is produced by mixing medium-chain triglycerides and long-chain triglycerides, then allowing hydrolysis to form free fatty acids, followed by random transesterification of the fatty acids into mixed triglyceride molecules. Studies in animals have shown an improvement in nitrogen balance with the use of these lipid emulsions. Only 8 human clinical studies with these products have been performed. The results of these human clinical studies have been less promising than the animal studies; however, an improvement in nitrogen balance and lipid metabolism exceeds results associated with infusion of long-chain triglycerides (LCT) or a physical mixture of long-chain triglycerides and medium-chain triglycerides (LCT-MCT). Structured-lipid emulsion seems to induce less elevation in serum liver function values compared with standard IVFEs. In addition, structured-lipid emulsions have no detrimental effect on the reticuloendothelial system. Further studies are necessary in order to recommend the use of structured-lipid emulsions. The clinical community hopes that chemically defined structured triglycerides will make it possible to determine the distribution of specific fatty acids on a specific position on the glycerol core and therefore obtain specific activity for a specific clinical situation.

Lipid and glucide sources in artificial nutrition

“…The use of SL in catabolic patients seems to improve nitrogen balance, preserve the function of the RES and decrease the incidence of liver impairment. The few available data on the immunologic activities of structured lipids do not show important effects [24,25].…”

Parenteral nutrition-associated liver disease and lipid emulsions

“…The result is a fat that contains LCTs and MCTs in the same glycerol and in a resulting equimolecular proportion. 8,12,16 It appears that fewer changes occur in the liver 17 and immune system 12 as compared with physical mixture or soybean emulsions.…”

The Optimal Lipid Formulation in Enteral Feeding in Critical Illness: Clinical Update and Review of the Literature

“…The use of structured lipids appears safe in the critically ill population, but strong data surrounding their efficacy as a beneficial fat during critical illness are lacking, especially when compared to a physical mixture of MCFAs and LCFAs. The structured lipids currently available in enteral formulas are mainly produced using a random re-esterification process, ie, fatty acids are randomly placed on the glycerol backbone [41].…”