Urinary excretion of 5-L-oxoproline (pyroglutamic acid) is increased during recovery from severe childhood malnutrition and responds to supplemental glycine

J Nutr. 1996 Nov;126(11):2823-30. doi: 10.1093/jn/126.11.2823.


We hypothesized that a limitation in the endogenous formation of glycine might constrain catch-up growth during recovery from severe childhood malnutrition. The urinary excretion of 5-L-oxoproline is increased when the glycine available for glutathione synthesis is limited. Urinary excretion of 5-L-oxoproline was measured throughout recovery in 12 children (aged 16 +/- 6 mo) with severe malnutrition. Urinary 5-L-oxoproline was similar at admission and after recovery, but was increased significantly during rapid catch-up growth. There was a significant relationship between the rate of weight gain and 5-L-oxoproline excretion in urine. In nine children (aged 15 +/- 5 mo), the effect of oral supplementation with glycine, [1.7 mmol/(kg x d) for 48 h] during rapid catch-up growth on 5-L-oxoprolinuria and blood glutathione concentration was determined. In seven of the nine children weight gain was less than 17 g/(kg x d) and following oral glycine supplements 5-L-oxoproline excretion was reduced up to 64% and blood glutathione concentration increased up to 100%. In the two children who were gaining weight at a rate > 17 g/(kg x d), glycine supplementation was associated with a further increase in 5-L-oxoproline excretion and a decrease in blood glutathione. If 5-L-oxoproline is an index of the relative availability of glycine, then the data indicate that glycine may be limiting during rapid catch-up growth. This would have important implications for repletion of muscle and gain in height.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / physiology
  • Body Weight / drug effects
  • Body Weight / physiology
  • Child, Preschool
  • Female
  • Food, Fortified
  • Glutathione / blood
  • Glycine / administration & dosage
  • Glycine / pharmacology*
  • Growth / drug effects
  • Growth / physiology
  • Humans
  • Infant
  • Male
  • Nutrition Disorders / urine*
  • Pyrrolidonecarboxylic Acid / urine*
  • Weight Gain / drug effects
  • Weight Gain / physiology


  • Glutathione
  • Pyrrolidonecarboxylic Acid
  • Glycine