Cranberries and Urinary Tract Infection (UTI): Assessment of the Evidence

Urinary tract infection (UTI), a common bacterial infection, occurs across myriad subject populations from individuals with bladder dysfunction to normal, healthy women. Cranberry has been used traditionally to prevent UTIs primarily by women prone to recurrent UTI, and a number of clinical studies have been published supporting its benefit. Two recent meta‐analyses have assessed the clinical evidence and, surprising, reported substantially different conclusions. One concluded cranberry juice cannot be recommended for the prevention of UTIs (Jepson et al. Cochrane Database Syst Rev. 2012; 10: 1‐80), whereas the other indicated cranberry products are associated with protective effects against UTIs (Wang et al. Arch Intern Med. 2012; 172: 988‐96). The objective of this study was to identify the factors that contributed to these disparate results. We conducted modeling analyses to identify pivotal studies and other factors contributing to the conclusions. Results indicate the studies used were substantially different, but this was not the main factor in the differing conclusions. In some cases, different datasets from the same studies were selected. Moreover, the Cochrane analysis was influenced by four main studies, none of which were performed in women with recurrent UTIs, the population for which cranberry products have shown the most evidence for benefit in clinical trials. In contrast, the Wang analysis included women with recurrent UTI, and weighted the evidence relatively equally across the populations (e.g., neuropathic bladder, children, elderly). Given the importance of this issue for the many women with recurrent UTIs, a clear assessment of the literature for this subgroup is warranted. Supported by Ocean Spray Cranberries, Inc.