February 2011, Volume 61, Issue 2

Letter to the Editor

Cranberry business and evidence-based prevention of urinary tract infection

Madame, Shirin Mirza1 concluded that the use of cranberry prevents UTIs. This was mainly based upon a cochrane review.2 However, the results of this Cochrane review should be interpreted with caution as the clinical evidence can, at the most, be categorized as level 2 (mid level). This Cochrane article reviewed 10 randomized controlled Trials (RCTs) or quasi-RCTs. The nature of cranberry products among different trials was not uniform to allow a good metanalysis. Seven trials used juice while four studied tablets while only one tried to study both juice and tablets. Six trials had dropout rate over 20%. Only two of these used intention-to-treat analysis. Hence this cannot be taken as highly reliable clinical evidence. Dynamed, EBM,3 AFP4 and other foraging experts rate the clinical evidence similarly.
Further clinical application of cranberry for prevention of UTI is limited for following more reasons
1- The preventive benefit was not observed among elderly men and women or patients with comorbid conditions like diabetes are catheterized or have neuropathic bladder secondary to some other condition or pregnant patients. This leaves us with a patient population where similar level of clinical evidence (level 2/mid level) exists for post-coital voiding.5
2- Significant side effects might limit its long term use which is required to have significant effect.
3- Cranberry increases oxalate excretion and may predispose to kidney stones.
4- Availability and cost of cranberry products in Pakistan might be a big problem for general population.
Abdul Waheed,1 Marium Tariq,2 Zafar-ul Ahsan3
Penn State University/The Good Samaritan Hospital, Family Medicine
Residency Program, Lebanon, PA, USA,1,2 Urology & Kidney Transplant
Department, Fatima Jinnah Medical College/Sir Ganga Ram Hospital, Lahore Pakistan.3


1.Mirza S. Recurrent urinary tract infection in women: can cranberry prevent it? J Pak Med Assoc 2010; 60: 609.
2.Jepson RG, Craig JC. Cranberries for preventing urinary tract infections. Cochrane Database Syst Rev 2008: CD001321
3.Andolsek KM. Review: cranberry products may prevent urinary tract infection in women with recurrent infections. Evid Based Med 2008; 13: 105.
4.Lynch DM. Cranberry for prevention of urinary tract infections. Am Fam Physician 2004; 70: 2175-7.
5.Foxman B, Frerichs RR. Epidemiology of urinary tract infection: II diet, clothing, and urination habbits. Am J Public Health 1985; 75: 1314-7.

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