Cranberry juice is commonly used as a natural preventative measure for urinary tract infections, particularly in individuals prone to recurrent infections. It contains compounds called proanthocyanidins, which may help prevent E. coli from adhering to the urinary tract lining, thereby reducing the risk of infection. 

However, cranberry juice is not effective for treating an active UTI and should not replace antibiotics when symptoms are present. Unsweetened cranberry juice or concentrated supplements are preferred, as many commercial juices are too diluted or high in sugar. While results vary, it is generally considered a safe and potentially helpful part of a UTI prevention strategy.