In vivo elongation and desaturation of linoleic acid (LA) to arachidonic acid (ARA) and a-linolenic (LNA) to docosahexaenoic acid (DHA) was studied in 15 preterm (bw 1740g, GA 31.3 wks), 8 term (bw 3557g, GA 40.1 wks) and 11 growth retarded (IUGR) (bw 1834, GA 35.6) neonates. They received 50 mg/kg bw of LA & LNA labeled with 5 deuterium (d5) enterally during the first days of life. D5 labeled derivatized fatty acids were determined in blood samples at 24,48 and 96 hrs after dosing. Lipids were extracted and fatty acid analyzed by GC and negative ion mass spectrometry HP 5989GCMS. Mean concentrations (mg/ml) and d5/d0 n-3 and n-6 fatty acids in plasma lipids are reported in the table, variability is high. d5 LA and LNA peaked at 24 hrs, d5 ARA & d5DHA were highest at 48 hours in term infants and at 96 hrs in preterm and IUGR infants. Our results suggest a slower rate of LCPUFA production in IUGR. Preterms had highest concentrations of d5 LCPUFA and d5/d0 at all times suggesting increased conversion. Neonates are able to produce LCPUFA, immature infants produce them faster.

Table 1 No caption available.
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