Use of cranberry for prophylaxis of uncomplicated recurrent urinary tract infections
European Association of Urology, 2010
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Over the last few years, an increase in the use of cranberry (C) has been noted for the following two reasons: i) the high number of UTIs has lead to increased antibiotic use and thus increased antibi- otic resistance; and ii) the main mecha- nisms of action in reducing UTIs have been identified. C inhibits the adherence of E.coli to uro-epithelial cells, the first and necessary step for UTI. This competi- tive inhibition is due to a non-dialyzable compound, a condensed tannin, the proanthocyanidin (PAC) type A. Among the three species of C vaccinium macro- carpon is only one to have PAC-A.
The first dosage used was 36 mg served as 300 ml of juice presentation (Avorn). In 2006, a double-blind randomised placebo- controlled cross-over trial comparing two dosages of C. juice presentation (250
and 750 ml) found a significant reduc- tion of E. coli adherence (p > 0,001) dose dependent.
In 2008 a double-blind randomised placebo-controlled cross-over trial tested a commercially available capsule of vac- cinium macrocarpon containing 36 mg of PAC. A statistically significant reduction of bacterial adherence of E. coli was found (p < 0,001), dose-dependent. For the first time this study established clearly thebio- activity of a C. capsule.
Two methods of PAC dosage are avail- able: the reference DMAC and NP-HPLC with a conversion factor of one to two (36 mgPACbyDMAC=72mgPACbyNP- HPLC).
Quantification of bio-activity in urine: Given that 36 mg of PAC per day is nec- essary to obtain a preventive clinical effect on UTIs (Avorn Study); and given that we lack a method to evaluate active
Chapter 4; 4.4 Prevention of recurrent urogenital tract infections in adult women
metabolites in urine, surrogates are needed to quantify bio-activity in urine. There are two surrogates: i) the red blood cell hemagglutination test (Howell)and ii) the direct cellular adhesion test (Lavigne).
Jepson and Craig have recently reviewed the clinical studies for the Cochrane database. Juice presentation is too unwieldy to be recommended for long periods of time as a prophylactic treat- ment for recurrent UTI, thus the neces- sity to develop capsules/tablets. However, there is no standardisation for these; not in C species, in method of PAC measure- ment, nor in dosage of PAC per day. Apart from one capsule, there is no data about the bio-activity of the commercially avail- able products, no dose-ranging and no direct correlation between in vitro and clinical effects.