Urinary pH is an indicator of dietary acid-base load in a population: results from the EPIC-Norfolk cohort study

Objective and design: We investigated the relationship between dietary PRAL (estimated using the EPIC-Norfolk FFQ) and pH measured in casual urine samples in a cross-sectional population study of 22,038 men and women, aged 39-78 years, from the Norfolk area of the UK (8,9). Urine pH was measured using AMES multiple reagent strips. Dietary PRAL was divided into gender specific quintiles for analysis and also adjusted for age, height, weight, physical activity, smoking habit, diagnosed high blood pressure, alcohol consumption, diuretic medication and the presence of urinary protein. Results: Mean PRAL intake was -4.51 mEq/d in men and -7.22 mEq/d in women. Mean urine pH was 6.0 units in both men and women. There was a difference of 0.2 of a unit of pH in both men and women between quintiles 1 and 5 of PRAL intake, which was significant both before and after adjustment for covariates (P for trend < 0.001). Conclusion: Despite the physiological influences determining urine pH and the potential error associated with using a casual urine sample, dietary acid-base load was associated with a measurable difference in urine pH within this population.