Dietary Protein and Potassium, Diet-Dependent Net Acid Load, and Risk of Incident Kidney Stones

Clin J Am Soc Nephrol. 2016 Oct 7;11(10):1834-1844. doi: 10.2215/CJN.01520216. Epub 2016 Jul 21.


Background and objectives: 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.

Design, setting, participants, & measurements: 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).

Results: 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; P value for trend <0.01). The hazard ratios for nondairy animal protein were 1.15 (95% confidence interval, 0.97 to 1.36; P value for trend =0.04) in the Health Professionals Follow-Up Study and 1.20 (95% confidence interval, 0.99 to 1.46; P value 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]; P values for trend <0.001). Animal protein-to-potassium ratio was associated with higher risk (P value for trend =0.004), even after adjustment for animal protein and potassium. Higher dietary potassium was associated with higher urine citrate, pH, and volume (P values for trend <0.002).

Conclusions: 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.

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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Calcium / urine
  • Citric Acid / urine
  • Dairy Products
  • Dietary Proteins*
  • Female
  • Follow-Up Studies
  • Health Surveys*
  • Humans
  • Hydrogen-Ion Concentration
  • Incidence
  • Kidney Calculi / epidemiology*
  • Male
  • Middle Aged
  • Oxalic Acid / urine
  • Potassium, Dietary*
  • Prospective Studies
  • United States / epidemiology
  • Uric Acid / urine
  • Urinalysis
  • Vegetables


  • Dietary Proteins
  • Potassium, Dietary
  • Uric Acid
  • Citric Acid
  • Oxalic Acid
  • Calcium