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Lysine kinetics in preterm infants: the importance of enteral feeding
  1. S R D van der Schoor1,
  2. P J Reeds,
  3. F Stellaard2,
  4. J D L Wattimena1,
  5. P J J Sauer2,
  6. H A Büller1,
  7. J B van Goudoever3
  1. 1Erasmus MC-Sophia Children’s Hospital, Department of Paediatrics, Dr Molewaterplein 60, 3015 GJ, Rotterdam, the Netherlands
  2. 2University Hospital Groningen, Department of Paediatrics, Hanzeplein 1, 9713 GZ Groningen, the Netherlands
  3. 3Erasmus MC-Sophia Children’s Hospital, Department of Paediatrics, Dr Molewaterplein 60, 3015 GJ, Rotterdam, the Netherlands, and USDA/ARS Children’s Nutrition Research Centre, Department of Paediatrics, Baylor College of Medicine, 1100 Bates St, Houston, TX, 77030, USA
  1. Correspondence to:
    Dr J B van Goudoever
    Erasmus MC-Sophia Children’s Hospital, Department of Paediatrics, Division of Neonatology, Dr Molewaterplein 60, 3015 GJ, Rotterdam, the Netherlands;


Introduction: Lysine is the first limiting essential amino acid in the diet of newborns. First pass metabolism by the intestine of dietary lysine has a direct effect on systemic availability. We investigated whether first pass lysine metabolism in the intestine is high in preterm infants, particularly at a low enteral intake.

Patients and methods: Six preterm infants (birth weight 0.9 (0.1) kg) were studied during two different periods: period A (n = 6): 40% of intake administered enterally, 60% parenterally; lysine intake 92 (6) μmol/(kg×h); and period B (n = 4): 100% enteral feeding; lysine intake 100 (3) μmol/(kg×h). Dual stable isotope tracer techniques were used to assess splanchnic and whole body lysine kinetics.

Results: Fractional first pass lysine uptake by the intestine was significantly higher during partial enteral feeding (period A 32 (10)% v period B 18 (7)%; p<0.05). Absolute uptake was not significantly different. Whole body lysine oxidation was significantly decreased during full enteral feeding (period A 44 (9) v period B 17 (3) μmol/(kg×h); p<0.05) so that whole body lysine balance was significantly higher during full enteral feeding (period A 52 (25) v period B 83 (3) μmol/(kg×h); p<0.05).

Conclusions: Fractional first pass lysine uptake was much higher during partial enteral feeding. Preterm infants receiving full enteral feeding have lower whole body lysine oxidation, resulting in a higher net lysine balance, compared with preterm infants receiving partial enteral feeding. Hence parenterally administered lysine is not as effective as dietary lysine in promoting protein deposition in preterm infants.

  • enteral nutrition
  • lysine metabolism
  • parenteral nutrition
  • LRP, lysine release from protein breakdown
  • NOLD, non-oxidative lysine disposal
  • PDB, Pee Dee Belemnite

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  • This paper is dedicated to the memory of P J Reeds. His passing in late 2002 represented an enormous loss for everyone who had the privilege of working with him. Dr Reeds was a great mentor and noble role model, who continues to provide inspiration to his former colleagues.