title: Effect of n-3 fatty acid supplementation on urinary risk factors for calcium oxalate stone formation.
abstract: OBJECTIVE
  Findings are inconsistent in a few studies of the effect of n-3 fatty acid supplementation on urinary calcium and oxalate excretion in stone formers. We evaluated the physiological effects of supplementation with eicosapentaenoic acid and docosahexaenoic acid on urinary risk factors for calcium oxalate stone formation under standardized conditions.
  
  
  METHODS
  We studied 15 healthy subjects initially while consuming a standardized diet for 5 days (control phase). During consecutive intervention phases 1-5-day standardized diet, 2-20-day free diet and 3-5-day standardized diet participants received 900 mg eicosapentaenoic acid and 600 mg docosahexaenoic acid daily. While ingesting the standardized diets, daily 24-hour urine samples were collected.
  
  
  RESULTS
  After short-term supplementation with eicosapentaenoic acid and docosahexaenoic acid in phase 1 we noted no changes in urinary parameters compared to the control phase. After 30-day supplementation with eicosapentaenoic acid and docosahexaenoic acid in phase 3 relative supersaturation with calcium oxalate decreased significantly by 23% from a mean ± SD of 2.01 ± 1.26 to 1.55 ± 0.84 due to significantly decreased urinary oxalate excretion (p = 0.023). Other urinary variables were not affected by supplementation.
  
  
  CONCLUSIONS
  Results show that 30-day n-3 fatty acid supplementation effectively decreases urinary oxalate excretion and the risk of calcium oxalate crystallization. The mechanism of the physiological effect may be decreased cellular oxalic acid exchange attributable to an altered fatty acid pattern of membrane phospholipids with concomitant changes in oxalate transporter activity. Calcium oxalate stone formers may benefit from long-term n-3 fatty acid supplementation.
authors.affiliation: Department of Urology, University of Bonn, Bonn, Germany. Roswitha.Siener@ukb.uni-bonn.de
authors.forename: Roswitha
authors.initials: R
authors.lastname: Siener
authors.forename: Brigitte
authors.initials: B
authors.lastname: Jansen
authors.forename: Bernhard
authors.initials: B
authors.lastname: Watzer
authors.forename: Albrecht
authors.initials: A
authors.lastname: Hesse
mesh_terms: D000284:Administration, Oral; D002129:Calcium Oxalate / Q000652:urine*; D015331:Cohort Studies; D019587:Dietary Supplements; D004281:Docosahexaenoic Acids / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D015118:Eicosapentaenoic Acid / Q000008:administration & dosage; D005231:Fatty Acids, Unsaturated / Q000008:administration & dosage*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007669:Kidney Calculi / Q000737:chemistry / Q000517:prevention & control; D008297:Male; D012016:Reference Values; D012307:Risk Factors; D016896:Treatment Outcome; D016482:Urinalysis; D014545:Urinary Calculi / Q000737:chemistry / Q000517:prevention & control*
chemical_list: D005231:Fatty Acids, Unsaturated; D004281:Docosahexaenoic Acids; D002129:Calcium Oxalate; D015118:Eicosapentaenoic Acid