341 Cholesterol Biosynthesis in Preterm Infants on Parenteral Nutrition with a Lipid Emulsion Containing 10% Fish Oil (FO): a Pilot Study

Background and Aims Limited data are available on the metabolic effects of intravenous fish oil (FO) in premature infant. We reported on the plasma cholesterol lowering effect of an intravenous lipid emulsion containing 10% FO or FMS (10% FO, 50% MCT, 40% soybean oil-SO) when compared with MS (50% MCT, 50% SO) (D’Ascenzo et al. JPediatr 2011). Aim of this study was to ascertain if the lower plasma cholesterol concentrations resulted from reduced biosynthesis or enhanced clearance. Methods Eighteen premature infants were randomised to receive FMS (n=9, GA 199±17 days, BW 983±138 g) or MS (n=9, GA 202±17 days, BW 992±178 g). The IV lipids were increased to 2.5 g∙kg –1 ∙d –1 in the first week of life. On day 7 patients received an oral dose of deuterated water for the measurement of cholesterol and palmitate biosynthesis. The incorporation of deuterium from water into cholesterol (cholesterol biosynthesis) was measured by Gas Chromatography and Combustion Isotope Ratio Mass Spectrometry (GC-C-IRMS). Fractional and Absolute Synthesis Rates (ASR) were obtained and compared by Mann-Whitney Test. Results Plasma free cholesterol concentrations were significantly lower in FMS than in MS (53±5 vs 64±9 mg/dl, p=0.01). ASR were 8.5±3.4 vs 8.4±2.6 mg/kg/d in FMS and MS respectively (p=0.93). Conclusions Intravenous FO in preterm infants has marked cholesterol lowering effect but cholesterol biosynthesis was not reduced. Measurements of cholesterol catabolism are in progress.