Cranberry (Vaccinium macrocarpon) has been used for decades to prevent urinary 
tract infections (UTIs) that are among the most common bacterial infections in 
women. As to the traditional use of cranberry and its A-type proanthocyanidins' 
ability to inhibit adherence of the bacterial P fimbriae in a dose-dependent 
manner, clinical trials have been conducted on different subpopulations. A 
Cochrane meta-analysis in 244 females with symptomatic UTI suggests that the 
effect was more pronounced in women with recurrent UTIs than elderly males and 
females or people requiring catheterization. A first head-to-head trial in older 
females has been published comparing effectiveness of a low-dose antibiotic 
versus cranberry in which investigators suggest that cranberry products may have 
a role in older females with recurrent UTI. Still with regard to antibiotic 
treatment in women, a recently published study investigated also the potential 
cranberry juice interaction with beta-lactam antibiotics supporting the 
hypothesis that cranberry juice in usual quantities as prophylaxis for UTI is 
not likely to alter the pharmacokinetics of these oral antibiotics. In addition, 
the effects of cranberry in pregnant female patients have been investigated. A 
first pilot trial has been published in which, while a possible protective 
effect was shown, more than one third of the females withdrew mainly for 
gastrointestinal upset.