Urological Research

, Volume 37, Issue 2, pp 63–68

Increased protein intake on controlled oxalate diets does not increase urinary oxalate excretion

  • John Knight
  • Linda H. Easter
  • Rebecca Neiberg
  • Dean G. Assimos
  • Ross P. Holmes
Original Paper

DOI: 10.1007/s00240-009-0170-z

Cite this article as:
Knight, J., Easter, L.H., Neiberg, R. et al. Urol Res (2009) 37: 63. doi:10.1007/s00240-009-0170-z

Abstract

High animal protein intake is a risk factor for calcium oxalate stone disease. The effect of dietary protein on the urinary excretion of calcium, acid and citrate is well established. However, its effect on oxalate excretion is unclear, due in part to an inadequate control of dietary oxalate intake in previous studies. This relationship warrants clarification due to the proposed important role of the metabolism of amino acids in endogenous oxalate synthesis. In this study, 11 normal subjects consumed controlled oxalate diets containing 0.6, 1.2 and 1.8 g protein/kg body weight/day. The analysis of 24 h urine collections confirmed that as protein intake increased, urinary calcium and glycolate increased and urinary pH and citrate decreased. The increased glycolate excretion was due in part to an increased hydroxyproline, but not glycolate consumption. Total daily urinary oxalate excretion did not change. When indexed to creatinine there was a small but significant decrease in oxalate excretion. This is most likely due to hyperfiltration. These results indicate that as dietary protein intake increases, the catabolism of diet-derived amino acids is not associated with an increased endogenous oxalate synthesis in normal subjects.

Keywords

Dietary protein Oxalate excretion Oxalate synthesis Glycolate Hydroxyproline 

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  • John Knight
    • 1
  • Linda H. Easter
    • 2
  • Rebecca Neiberg
    • 3
  • Dean G. Assimos
    • 1
  • Ross P. Holmes
    • 1
  1. 1.Department of UrologyWake Forest University School of MedicineWinston-SalemUSA
  2. 2.GCRC Bionutrition UnitWake Forest University School of MedicineWinston-SalemUSA
  3. 3.Department of Public Health SciencesWake Forest University School of MedicineWinston-SalemUSA