title: Impact of dietary calcium and oxalate, and Oxalobacter formigenes colonization on urinary oxalate excretion.
abstract: OBJECTIVE
  Enteric colonization with Oxalobacter formigenes, a bacterium whose main energy source is oxalate, has been demonstrated to decrease the risk of recurrent calcium oxalate kidney stone formation. We assessed the impact of diets controlled in calcium and oxalate contents on urinary and fecal analytes in healthy subjects who were naturally colonized with O. formigenes or not colonized with O. formigenes.
  
  
  METHODS
  A total of 11 O. formigenes colonized and 11 noncolonized subjects were administered diets controlled in calcium and oxalate contents. We assayed 24-hour urine collections and stool samples obtained on the last 4 days of each 1-week diet for stone risk parameters and O. formigenes levels. Mixed model analysis was used to determine the effects of colonization status on these variables.
  
  
  RESULTS
  Urinary calcium and oxalate excretion were significantly altered by the dietary changes in O. formigenes colonized and noncolonized individuals. Mixed model analysis showed significant interaction between colonization status and oxalate excretion on a low calcium (400 mg daily)/moderate oxalate (250 mg daily) diet (p = 0.026). Urinary oxalate excretion was 19.5% lower in O. formigenes colonized subjects than in noncolonized subjects on the low calcium/moderate oxalate diet (mean ± SE 34.9 ± 2.6 vs 43.6 ± 2.6 mg, p = 0.031).
  
  
  CONCLUSIONS
  Results suggest that O. formigenes colonization decreases oxalate excretion during periods of low calcium and moderate oxalate intake.
authors.affiliation: Department of Microbiology and Biotechnology, Northeast Agricultural University (JJ), Harbin, People's Republic of China.
authors.forename: Juquan
authors.initials: J
authors.lastname: Jiang
authors.forename: John
authors.initials: J
authors.lastname: Knight
authors.forename: Linda H
authors.initials: LH
authors.lastname: Easter
authors.forename: Rebecca
authors.initials: R
authors.lastname: Neiberg
authors.forename: Ross P
authors.initials: RP
authors.lastname: Holmes
authors.forename: Dean G
authors.initials: DG
authors.lastname: Assimos
mesh_terms: D000328:Adult; D001691:Biological Therapy; D002136:Calcium, Dietary / Q000008:administration & dosage*; D005243:Feces / Q000737:chemistry; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000517:prevention & control; D008297:Male; D010070:Oxalates / Q000008:administration & dosage* / Q000032:analysis* / Q000652:urine; D020624:Oxalobacter formigenes
chemical_list: D002136:Calcium, Dietary; D010070:Oxalates