Hepatic de novo lipogenesis in stable low-birth-weight infants during exclusive breast milk feedings and during parenteral nutrition.
BACKGROUND
Low-birth-weight (LBW) infants have high energy requirements and are dependent on high fat intake to maintain adequate postnatal growth. Fat energy is transported in plasma as triglycerides, which are either derived from the diet or from de novo lipogenesis (DNL). It is our hypothesis that DNL plays an important physiologic role in adapting to exclusive breast milk (EBM) feeding or to parenteral nutrition (PN).


METHODS
We studied hepatic de novo lipogenesis in 14 LBW (<34-week gestation) appropriate for gestational age and receiving either EBM feedings or full PN support. Stable isotope tracer [2-(13)C] acetate was administered for 72 hours to achieve an estimated 10% enrichment of daily fat intake. Fatty acids were extracted from plasma for gas chromatography-mass spectrometry analyses.


RESULTS
Percent new synthesis of palmitate was 13.1% +/- 2.5% in the EBM group and 14.9% +/- 0.7% in the PN group (NS), stearate was 11.1% +/- 2.7% in the EBM group and 10.6% +/- 14% in the PN group (NS) and cholesterol was 12.7% +/- 2.1% in the EBM group and 17.4% +/- 4.6% in the PN group (NS) after 72 hours of tracer administration (mean +/- SEM). The plasma lipid fatty acid composition in palmitate, oleate, and stearate with intake of 3.6 +/- 0.6 g/kg/d of IV lipids (ILs) was similar to EBM-feeding infants taking 6.3 +/- 0.13 g/kg/d of fat.


CONCLUSIONS
De novo lipogenesis is active in stable LBW infants maintaining standard postnatal growth. Hepatic DNL permits newborn infants to meet the fat energy needs of peripheral tissues for growth and storage and to maintain plasma fatty acid composition in adaptation to different dietary fat intake.
Garg
Meena
M
Department of Pediatrics, Mattel Children's Hospital at UCLA, David Geffen School of Medicine, 10833 Le Conte Avenue, Room B2-375 MDCC, Los Angeles, CA 90095, USA. mgarg@mednet.ucla.edu
Bassilian
Sara
S
Bell
Cynthia
C
Lee
Samuel
S
Lee
W N Paul
WN
D000222:Adaptation, Physiological; D001724:Birth Weight; D001942:Breast Feeding; D002247:Carbon Isotopes; D004041:Dietary Fats / Q000008:administration & dosage; D004734:Energy Metabolism / Q000502:physiology; D005227:Fatty Acids / Q000032:analysis; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D005865:Gestational Age; D006801:Humans; D007230:Infant, Low Birth Weight / Q000254:growth & development / Q000378:metabolism* / Q000502:physiology*; D007231:Infant, Newborn; D050356:Lipid Metabolism; D008055:Lipids / Q000096:biosynthesis*; D008099:Liver / Q000378:metabolism*; D008297:Male; D009751:Nutritional Requirements; D010288:Parenteral Nutrition; D015430:Weight Gain
D002247:Carbon Isotopes; D004041:Dietary Fats; D005227:Fatty Acids; D008055:Lipids