The effect of different diets on urine composition and the risk of calcium oxalate crystallisation in healthy subjects

Eur Urol. 2002 Sep;42(3):289-96. doi: 10.1016/s0302-2838(02)00316-0.


Objective: The aim of the study was to determine the impact of defined diet modifications on urine composition and the risk of calcium oxalate crystallisation.

Methods: Ten healthy male volunteers consumed a self-selected diet (SD) for 14 days, and three different standard diets for a period of 5 days each. Whereas the western-type diet (WD) is representative of the usual dietary habits, the normal mixed diet (ND) and the ovo-lacto-vegetarian diet (VD) were calculated according to the requirements.

Results: The risk of calcium oxalate crystallisation, calculated as relative supersaturation (EQUIL2) from urine composition, was highest during ingestion of diets SD and WD. The intake of diet ND resulted in a significant decrease in relative supersaturation with calcium oxalate by 58% (p<0.05) compared with diet WD, due to a significant decline in urinary calcium and uric acid excretion and a significant increase in urinary volume, pH-value and citrate excretion. In spite of an increase in urinary pH, citrate and magnesium excretion and a decline in calcium excretion, no further significant decrease in the risk of calcium oxalate crystallisation was observed on diet VD, due to a significant increase in urinary oxalate by 30% (p<0.05) on average.

Conclusions: The change of usual dietary habits for a normal mixed diet significantly reduces the risk of calcium oxalate crystallisation. With a vegetarian diet a similar decline in urinary supersaturation with calcium oxalate can be achieved compared to a normal mixed diet. Since urinary oxalate excretion increased significantly, a vegetarian diet without adequate intake of calcium may not be recommended to patients with mild hyperoxaluria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Calcium / urine
  • Calcium Oxalate / chemistry
  • Calcium Oxalate / urine*
  • Citrates / urine
  • Crystallization
  • Diet / adverse effects*
  • Humans
  • Magnesium / urine
  • Male
  • Oxalates / urine
  • Treatment Outcome
  • Uric Acid / urine
  • Urinary Calculi / etiology*
  • Urinary Calculi / metabolism
  • Urinary Calculi / urine
  • Urine / chemistry*
  • Urine / physiology


  • Citrates
  • Oxalates
  • Calcium Oxalate
  • Uric Acid
  • Magnesium
  • Calcium