EFFECT OF CRANBERRY JUICE CONSUMPTION ON URINARY STONE RISK FACTORS
Accepted 26 October 2004.
ABSTRACT
Purpose
We evaluated the effect of cranberry juice on urinary stone risk factors.
Materials and Methods
A total of 12 normal subjects and 12 calcium oxalate stone formers underwent 2, 7-day phases of study in random order while on a controlled metabolic diet. Subjects ingested 1 l of cranberry juice (CBJ) daily in 1 phase and 1 l of deionized water in the other phase. On the last 2 days of each phase 2, 24-hour urine collections and blood samples were obtained for stone risk factors and serum chemistries.
Results
No significant differences were found between normal subjects and stone formers in response to CBJ and, therefore, the groups were combined. CBJ significantly increased urinary calcium (from 154 to 177 mg per day, p =0.0008) and urinary oxalate (from 26.4 to 29.2 mg per day, p =0.04), thereby increasing urinary saturation of calcium oxalate by 18%. Urinary citrate was unchanged and urinary magnesium increased slightly. Urinary pH decreased (from 5.97 to 5.67, p =0.0005), and urinary ammonium, titratable acidity and net acid excretion increased during CBJ ingestion. Urinary uric acid decreased (from 544 to 442 mg per day, p <0.0001) as did serum uric acid. Thus, the urinary saturation of brushite and monosodium urate was reduced by CBJ but the amount of undissociated uric acid increased.
Conclusions
CBJ exerts a mixed effect on urinary stone forming propensity. It reduces urinary pH likely by providing an acid load and decreases urinary uric acid perhaps by retarding urate synthesis. Overall CBJ increases the risk of calcium oxalate and uric acid stone formation but decreases the risk of brushite stones.
Department of Urology, Mayo Clinic, Rochester, Minnesota (MTG), and the Department of Urology (KO, MSP), Jane and Charles Pak Center for Mineral Metabolism and Clinical Research (LJB, BAH, CYCP, MSP), University of Texas Southwestern Medical Center, Dallas, Texas
Nothing to disclose.
Correspondence: Department of Urology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390-9110 (telephone: 214-648-6853; FAX: 214-648-8786).
Financial interest and/or other relationship with Cook Urological, Inc., Applied Medical, Boston Scientific and Percutaneous Systems, Inc.
Supported by United States Public Health Service Grants M01-RR00633 and P01-DK20543 from the National Institutes of Health.
Study received Institutional Review Board approval.
Editor’s Note: This article is the third of 5 published in this issue for which category 1 CME credits can be earned. Instructions for obtaining credits are given with the questions on pages 800 and 801.
ABSTRACT