British Journal of Nutrition

Full Papers

Urine pH is an indicator of dietary acid–base load, fruit and vegetables and meat intakes: results from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk population study

Ailsa A. Welcha1 c1, Angela Mulligana1, Sheila A. Binghama2 and Kay-tee Khawa3

a1 Department of Public Health and Primary Care, University of Cambridge, Strangeways Site, Wort's Causeway, Cambridge CB1 8RN, UK

a2 Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 2XY, UK

a3 Clinical Gerontology Unit, University of Cambridge, Cambridge CB2 2QQ UK


Evidence exists that a more acidic diet is detrimental to bone health. Although more precise methods exist for measurement of acid–base balance, urine pH reflects acid–base balance and is readily measurable but has not been related to habitual dietary intake in general populations. The present study investigated the relationship between urine pH and dietary acid–base load (potential renal acid load; PRAL) and its contributory food groups (fruit and vegetables, meats, cereal and dairy foods). There were 22 034 men and women aged 39–78 years living in Norfolk (UK) with casual urine samples and dietary intakes from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Norfolk FFQ. A sub-study (n 363) compared pH in casual samples and 24 h urine and intakes from a 7 d diary and the FFQ. A more alkaline diet (low PRAL), high fruit and vegetable intake and lower consumption of meat was significantly associated with a more alkaline urine pH before and after adjustment for age, BMI, physical activity and smoking habit and also after excluding for urinary protein, glucose, ketones, diagnosed high blood pressure and diuretic medication. In the sub-study the strongest relationship was found between the 24 h urine and the 7 d diary. In conclusion, a more alkaline diet, higher fruit and vegetable and lower meat intake were related to more alkaline urine with a magnitude similar to intervention studies. As urine pH relates to dietary acid–base load its use to monitor change in consumption of fruit and vegetables, in individuals, warrants further investigation.

(Received April 04 2007)

(Revised August 26 2007)

(Accepted September 30 2007)

(Online publication November 28 2007)


c1 Corresponding author: Dr Ailsa Welch, fax +44 1223 740177, email


Abbreviations: EPIC, European Prospective Investigation into Cancer and Nutrition; PRAL, potential renal acid load