Triglyceride Hydrolysis of Soy Oil vs Fish Oil Emulsions

BACKGROUND: Fish oil triglycerides (TG) are being considered for use in IV lipid emulsions, but the characteristics of their lipase-mediated clearance from plasma are largely unknown. METHODS: We compared the in vitro hydrolysis of soy oil long-chain triglyceride emulsions (LCT) and fish oil emulsions (omega-3) using lipoprotein (LPL) and hepatic (HL) lipases, omega-3 emulsions contained 18% and 28% of total TG fatty acid as eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA), respectively. RESULTS: Under conditions of maximal hydrolysis, total free fatty acid (FFA) release was two- to threefold greater with LCT compared with omega-3 emulsions. Also, EPA and DHA together contributed proportionally much less than other fatty acids (< 20%) to FFA released from omega-3 emulsions. In mixtures of LCT emulsion with omega-3 emulsions, the presence of > 20% of omega-3 particles substantially inhibited LCT emulsion hydrolysis (by up to 50%). CONCLUSIONS: Our results suggest that, during infusion of omega-3 emulsions, EPA and DHA may enter cells as TG or partial glycerides within emulsion particles and not as FFA and that coinfusion of omega-3 emulsion with LCT emulsion at low omega-3:LCT emulsion ratios (up to 20% of total triglyceride as omega-3) will not substantially inhibit LCT hydrolysis.