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August 24, 1994

Reduction of Bacteriuria and Pyuria Using Cranberry Juice-Reply

Author Affiliations

Harvard Medical School Boston, Mass

JAMA. 1994;272(8):589-590. doi:10.1001/jama.1994.03520080030025

In Reply.  —Dr Hamilton-Miller raises an interesting mechanistic question. However, similarly high concentrations of quinic acid were added to the placebo beverage to mimic the taste of cranberries, making this explanation less likely. Moreover, benzoate is very widespread as a preservative in common foods, occurring in higher concentrations in soft drinks (170 to 420 ppm) than in standard cranberry-based beverages (40 to 50 ppm). The pKa of all these organic acids is about 4, so they would exist in a predominantly ionized state at the pH of urine. If the effect of cranberry juice on bacteriuria is real, a likelier mechanism may be the inhibition of bacterial adherence to the mucosal surface.1We agree with Dr Goodfriend that catheterized urine specimens represent a criterion standard. However, by using careful technique, we succeeded in obtaining samples without bacteriuria (using the standard definition) in about three fourths of all samples,

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