title: Caffeine intake and the risk of kidney stones.
abstract: BACKGROUND
  Although caffeine intake may increase urine calcium excretion, caffeine-containing beverages have been associated with a lower risk of nephrolithiasis.
  
  
  OBJECTIVE
  We sought to determine the association between caffeine intake and the risk of incident kidney stones in 3 large prospective cohorts.
  
  
  METHODS
  We prospectively analyzed the association between intake of caffeine and incidence of kidney stones in 3 large ongoing cohort studies, the Health Professionals Follow-Up Study (HPFS) and the Nurses' Health Studies (NHS) I and II. Information on the consumption of caffeine and the incidence of kidney stones was collected by validated questionnaires.
  
  
  RESULTS
  The analysis included 217,883 participants; over a median follow-up of >8 y, 4982 incident cases occurred. After multivariate adjustment for age, BMI, fluid intake, and other factors, participants in the highest quintile of caffeine intake had a 26% (95% CI: 12%, 38%) lower risk of developing stones in the HPFS cohort, a 29% lower risk (95% CI: 15%, 41%) in the NHS I cohort, and a 31% lower risk (95% CI: 18%, 42%) in the NHS II cohort (P-trend < 0.001 for all cohorts). The association remained significant in the subgroup of participants with a low or no intake of caffeinated coffee in the HPFS cohort. Among 6033 participants with 24-h urine data, the intake of caffeine was associated with higher urine volume, calcium, and potassium and with lower urine oxalate and supersaturation for calcium oxalate and uric acid.
  
  
  CONCLUSIONS
  Caffeine intake is independently associated with a lower risk of incident kidney stones.
authors.affiliation: From the Division of Nephrology-Renal Program, Department of Medical Sciences, Catholic University of the Sacred Heart, Rome, Italy (PMF and GG); the Channing Division of Network Medicine (PMF, ENT, and GCC) and the Renal Division (GCC), Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and the Division of Nephrology and Transplantation, Maine Medical Center, Portland, ME (ENT).
authors.forename: Pietro Manuel
authors.initials: PM
authors.lastname: Ferraro
authors.affiliation: From the Division of Nephrology-Renal Program, Department of Medical Sciences, Catholic University of the Sacred Heart, Rome, Italy (PMF and GG); the Channing Division of Network Medicine (PMF, ENT, and GCC) and the Renal Division (GCC), Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and the Division of Nephrology and Transplantation, Maine Medical Center, Portland, ME (ENT).
authors.forename: Eric N
authors.initials: EN
authors.lastname: Taylor
authors.affiliation: From the Division of Nephrology-Renal Program, Department of Medical Sciences, Catholic University of the Sacred Heart, Rome, Italy (PMF and GG); the Channing Division of Network Medicine (PMF, ENT, and GCC) and the Renal Division (GCC), Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and the Division of Nephrology and Transplantation, Maine Medical Center, Portland, ME (ENT).
authors.forename: Giovanni
authors.initials: G
authors.lastname: Gambaro
authors.affiliation: From the Division of Nephrology-Renal Program, Department of Medical Sciences, Catholic University of the Sacred Heart, Rome, Italy (PMF and GG); the Channing Division of Network Medicine (PMF, ENT, and GCC) and the Renal Division (GCC), Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA; and the Division of Nephrology and Transplantation, Maine Medical Center, Portland, ME (ENT).
authors.forename: Gary C
authors.initials: GC
authors.lastname: Curhan
mesh_terms: D000328:Adult; D000368:Aged; D015992:Body Mass Index; D002110:Caffeine / Q000008:administration & dosage*; D002118:Calcium / Q000652:urine; D002129:Calcium Oxalate / Q000652:urine; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007669:Kidney Calculi / Q000453:epidemiology*; D008019:Life Style; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011188:Potassium / Q000652:urine; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014527:Uric Acid / Q000652:urine
chemical_list: D002129:Calcium Oxalate; D014527:Uric Acid; D002110:Caffeine; D011188:Potassium; D002118:Calcium
keywords: caffeine; coffee; kidney stones; nutrition; prospective study