Fatty acid profile of modern lipid emulsions: Scientific considerations for creating the ideal composition

Abstract

Summary The inflammatory response, although essential for fighting infection, may damage the host. Its strength depends on pro- and anti-inflammatory mediators. Key among these mediators are cytokines and lipid mediators. Intravenous lipids meet the energy requirements of patients without the metabolic burden imposed by high-level glucose infusion. The first solutions developed were rich in ω -6 fatty acids. Meta-analyses suggested that these had detrimental effects albeit there is not much clinical evidence. Recent studies suggest that increasing the ratio of ω -3 to ω -6 fatty acids and raising the monounsaturated fatty acid (MUFA) content of intravenous lipid emulsion is beneficial. MUFAs exert a neutral effect on metabolism. In soybean oil-based emulsions the ratio of ω -6 to ω -3 fatty acids is approximately 7:1. These classes of fatty acids compete for inclusion in cell membranes and result in the production of lipid mediators of differing potency. The former are more potent than the latter. In post-operative patients infused with mixtures of soybean and fish oil to give ω -6 and ω -3 fatty acid ratios ranging from 6.75:1 to 0.08:1, the ratio of production of lower-potency to higher-potency leukotrienes, by PBMCs, was highest when a mixture of 2:1 was given. Thus ideal lipid solutions can be designed by adjustment of the ratio of ω -3, ω -6 and MUFAs.