title: Dietary risk factors for hyperoxaluria in calcium oxalate stone formers.
abstract: BACKGROUND
  Hyperoxaluria is a major predisposing factor in calcium oxalate urolithiasis. The aim of the present study was to clarify the role of dietary oxalate in urinary oxalate excretion and to assess dietary risk factors for hyperoxaluria in calcium oxalate stone patients.
  
  
  METHODS
  Dietary intakes of 186 calcium oxalate stone formers, 93 with hyperoxaluria (>or=0.5 mmol/day) and 93 with normal oxalate excretion (<0.4 mmol/day), were assessed by a 24-hour weighed dietary record. Each subject collected 24-hour urine during the completion of the food record. Oxalate content of foods was measured by a recently developed analytical method.
  
  
  RESULTS
  The mean daily intakes of energy, total protein, fat and carbohydrates were similar in both groups. The diets of the patients with hyperoxaluria were estimated to contain 130 mg/day oxalate and 812 mg/day calcium as compared to 101 mg/day oxalate and 845 mg/day calcium among patients without hyperoxaluria. These differences were not significant. The mean daily intakes of water (in food and beverages), magnesium, potassium, dietary fiber and ascorbic acid were greater in patients with hyperoxaluria than in stone formers with normal oxalate excretion. Multiple logistic regression analysis revealed that urinary oxalate excretion was significantly associated with dietary ascorbate and fluid intake, and inversely related to calcium intake. Differences of estimated diet composition of both groups corresponded to differences in urinary parameters.
  
  
  CONCLUSIONS
  These findings suggest that hyperoxaluria predominantly results from increased endogenous production and from intestinal hyperabsorption of oxalate, partly caused by an insufficient supply or low availability of calcium for complexation with oxalate in the intestinal lumen.
authors.affiliation: Department of Urology, and Institute of Medical Biometry, Informatics and Epidemiology, University of Bonn, Bonn, Germany. Roswitha.Siener@ukb.uni-bonn.de
authors.forename: Roswitha
authors.initials: R
authors.lastname: Siener
authors.forename: Dagmar
authors.initials: D
authors.lastname: Ebert
authors.forename: Claudia
authors.initials: C
authors.lastname: Nicolay
authors.forename: Albrecht
authors.initials: A
authors.lastname: Hesse
mesh_terms: D000328:Adult; D002118:Calcium / Q000097:blood; D002129:Calcium Oxalate / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006959:Hyperoxaluria / Q000178:diet therapy / Q000453:epidemiology* / Q000378:metabolism; D008274:Magnesium / Q000652:urine; D008297:Male; D008875:Middle Aged; D015596:Nutrition Assessment; D010070:Oxalates / Q000493:pharmacokinetics; D011188:Potassium / Q000652:urine; D012307:Risk Factors; D014527:Uric Acid / Q000097:blood; D014545:Urinary Calculi / Q000178:diet therapy / Q000453:epidemiology* / Q000378:metabolism
chemical_list: D010070:Oxalates; D002129:Calcium Oxalate; D014527:Uric Acid; D008274:Magnesium; D011188:Potassium; D002118:Calcium