title: Dietary Protein and Potassium, Diet-Dependent Net Acid Load, and Risk of Incident Kidney Stones.
abstract: Protein and potassium intake and the resulting diet-dependent net acid load may affect kidney stone formation. It is not known whether protein type or net acid load is associated with risk of kidney stones.
  
  
  
  We prospectively examined intakes of protein (dairy, nondairy animal, and vegetable), potassium, and animal protein-to-potassium ratio (an estimate of net acid load) and risk of incident kidney stones in the Health Professionals Follow-Up Study (n=42,919), the Nurses' Health Study I (n=60,128), and the Nurses' Health Study II (n=90,629). Multivariable models were adjusted for age, body mass index, diet, and other factors. We also analyzed cross-sectional associations with 24-hour urine (n=6129).
  
  
  
  During 3,108,264 person-years of follow-up, there were 6308 incident kidney stones. Dairy protein was associated with lower risk in the Nurses' Health Study II (hazard ratio for highest versus lowest quintile, 0.84; 95% confidence interval, 0.73 to 0.96;Pvalue for trend <0.01). The hazard ratios for nondairy animal protein were 1.15 (95% confidence interval, 0.97 to 1.36;Pvalue for trend =0.04) in the Health Professionals Follow-Up Study and 1.20 (95% confidence interval, 0.99 to 1.46;Pvalue for trend =0.06) in the Nurses' Health Study I. Potassium intake was associated with lower risk in all three cohorts (hazard ratios from 0.44 [95% confidence interval, 0.36 to 0.53] to 0.67 [95% confidence interval, 0.57 to 0.78];Pvalues for trend <0.001). Animal protein-to-potassium ratio was associated with higher risk (Pvalue for trend =0.004), even after adjustment for animal protein and potassium. Higher dietary potassium was associated with higher urine citrate, pH, and volume (Pvalues for trend <0.002).
  
  
  
  Kidney stone risk may vary by protein type. Diets high in potassium or with a relative abundance of potassium compared with animal protein could represent a means of stone prevention.
authors.affiliation: Division of Nephrology, Fondazione Policlinico Universitario "A. Gemelli", Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Pietro Manuel
authors.initials: PM
authors.lastname: Ferraro
authors.affiliation: Renal Division, Department of Medicine and.
authors.forename: Ernest I
authors.initials: EI
authors.lastname: Mandel
authors.affiliation: Renal Division, Department of Medicine and.|Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; and.
authors.forename: Gary C
authors.initials: GC
authors.lastname: Curhan
authors.affiliation: Division of Nephrology, Fondazione Policlinico Universitario "A. Gemelli", Catholic University of the Sacred Heart, Rome, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gambaro
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts; and.|Division of Nephrology and Transplantation, Maine Medical Center, Portland, Maine.
authors.forename: Eric N
authors.initials: EN
authors.lastname: Taylor
mesh_terms: D000328:Adult; D000818:Animals; D002118:Calcium / Q000652:urine; D019343:Citric Acid / Q000652:urine; D003611:Dairy Products; D004044:Dietary Proteins; D005260:Female; D005500:Follow-Up Studies; D006306:Health Surveys; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015994:Incidence; D007669:Kidney Calculi / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D019815:Oxalic Acid / Q000652:urine; D017419:Potassium, Dietary; D011446:Prospective Studies; D014481:United States / Q000453:epidemiology; D014527:Uric Acid / Q000652:urine; D016482:Urinalysis; D014675:Vegetables
chemical_list: D004044:Dietary Proteins; D017419:Potassium, Dietary; D014527:Uric Acid; D019343:Citric Acid; D019815:Oxalic Acid; D002118:Calcium
keywords: Body Mass Index; Citrates; Citric Acid; Cross-Sectional Studies; Diet; Dietary Proteins; Epidemiologic Studies; Follow-Up Studies; Kidney Calculi; NEAP; Potassium, Dietary; Risk; Vegetables; acid load; kidney stones; nutrition; potassium; protein; urolithiasis