Antifungal properties of cranberry juice.

Cranberry juice exerts a significant in vitro antifungal effect on eight representative species of dermatophytes, whereas it has no apparent effect on Candida albicans. The antifungal effect is fungistatic. Benzoic acid or other small molecular weight components, or both, were responsible for the fungistatic action. Studies with C. albicans on the effect of pH alone and the effect of pH on the ionization of benzoic acid indicate that cranberry juice would exert an even more significant antifungal action if the pH were left at its native value of 2.8; not adjusted to 5.6. This would probably be due to pH and a larger amount of free benzoic acid. Further investigation suggested that benzoic acid loses some of its antifungal properties in cranberry juice at pH 5.6. This investigation suggests that the dermatophytes may have a higher sensitivity to benzoic acid or other small molecular weight components of cranberry juice, or to both.