Effect of Cranberry Capsules on Bacteriuria Plus Pyuria

Shirin Zadeh, Mercer University College of Pharmacy

Bacteriuria is stated to result in an increase in antibiotic resistance and morbidity.1  Research over several decades has revealed its utility for urinary tract infection prevention.2 The American Academy of Family Physician guideline on urinary tract infection has suggested that the use of cranberry for up to 12 months is safe and moderately effective.3

Effect of Cranberry Capsules on Bacteriuria Plus Pyuria Among Older Women in Nursing Homes4
Design Double-blind, randomized, placebo-controlled; N= 185
Objective To test the effect of oral cranberry capsules on treatment of bacteriuria plus pyuria
Study Groups Cranberry capsules (n= 92); placebo (n= 93)
Methods Nursing home residents were randomly assigned to take two oral cranberry capsules (72 mg total, equivalent to 20 ounces of cranberry juice) or placebo once a day. The presence of bacteriuria plus pyuria was assessed every two months over the one-year study surveillance.


Duration August 24, 2012- October 26, 2015
Primary Outcome Measure Presence of bacteriuria plus pyuria
Baseline Characteristics Treatment Placebo
Mean age, years (SD) 87.1 (8.4) 85.6 (8.0)
Bacteriuria plus pyuria, n (%) 26 (28.3) 32 (34.4)
Results Bacteriuria plus pyuria, %
Treatment Placebo
2 months 27.6 34.6
4 months 23.8 40.0
6 months 20.3 29.9
8 months 25.5 23.3
10 months 29.4 24.1
12 months 27.3 19.6
Overall 25.5 29.5
Adverse Events Common Adverse Events: N/A
Serious Adverse Events: N/A
Percentage that Discontinued due to Adverse Events: N/A
Study Author Conclusions Aministration of cranberry capsules versus placebo resulted in no significant difference in the presence of bacteriuria plus pyuria over one year.



In this trial, there was an initial effect on bacteriuria plus pyuria in the first six months, but these rates returned to baseline in the second 6 months of study. Insignificant results could be due to a slightly lower adherence in the second six months. Additionally, it is possible that because of worsening incontinence and changes in the vaginal microbiome with age, the effects of cranberry capsules were not sustained. The specific role of cranberry capsules for prevention of new occurrence or reduction of bacteriuria plus pyuria is unfeasible.



  1. Stapleton AE, Dziura J, Hooton TM, et al. Recurrent urinary tract infection and urinary Escherichia coli in women ingesting cranberry juice daily: a randomized controlled trial. Mayo Clin Proc. 2012;87(2):143-50.
  2. Raz R, Chazan B, Dan M. Cranberry juice and urinary tract infection. Clin Infect Dis. 2004;38(10):1413-9.
  3. American Academy of Family Physician. Cranberry for Prevention of Urinary Tract Infections. Available at: http://www.aafp.org/afp/2004/1201/p2175.html. Accessed November 6, 2016.
  4. Juthani-mehta M, Van ness PH, Bianco L, et al. Effect of Cranberry Capsules on Bacteriuria Plus Pyuria Among Older Women in Nursing Homes: A Randomized Clinical Trial. JAMA. 2016.



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