Literature Review of Ascorbic Acid, Cranberry, and D-mannose for Urinary Tract Infection Prophylaxis in Older People

Background Urinary tract infections (UTIs) are the most prevalent infections in older patients with the potential for morbidity and mortality. Antibiotics are not generally recommended for UTI prophylaxis in this population. There is interest among the public and health providers to try over-the-counter products, such as cranberry, D-mannose, and vitamin C. The objective of this analysis was to review the literature for the efficacy and tolerability of these supplements in older individuals. Methods A literature review was conducted on PubMed using the search terms urinary tract infection or UTI, prevention/prophylaxis, cranberry, D-mannose, vitamin C/ascorbic acid. Few studies were conducted among older people; therefore, the authors included studies of all adults who had recurrent UTIs or were at increased risk of UTIs. Level (quality) of evidence were determined using the ACC/AHA Clinical Practice Guideline Recommendation Classification System. Results A total of 24 studies were included. This review captured all studies in previous reviews as well as recent publications. The authors determined that there were limited data for D-mannose and vitamin C, and randomized data for cranberry as defined by the classification system. Conclusions The three supplements reviewed appear not to be strongly supported by clinical data. For those who are interested in trying these products despite the lack of robust evidence for clinical efficacy, it may be helpful to know that the studies included in this review did not identify any clinically important signs of harm, to the extent that safety data were documented and reported.