Background: Urinary tract infection (UTI) prevention benefits of cranberry intake are clinically validated, especially for women and children. To ensure the benefits of cranberry dietary supplement products, the anti-adhesion activity (AAA) against uropathogenic bacteria is routinely used in in vitro bioassays to determine the activity in whole product formulations, isolated compounds, and ex vivo bioassays to assess urinary activity following intake. D-mannose is another dietary supplement taken for UTI prevention, based on the anti-adhesion mechanism.

Objective: Compare the relative AAA of cranberry and D-mannose dietary supplements against the most important bacterial types contributing to the pathogenesis of UTI and consider how certain components potentially induce in vivo activity.

Methods: The current study used a crossover design to determine ex vivo AAA against both P- and Type 1-fimbriated uropathogenic Escherichia coli of either D-mannose or a cranberry fruit juice dry extract product containing 36 mg of soluble proanthocyanidins (PACs), using bioassays that measure urinary activity following consumption. AAA of extracted cranberry compound fractions and D-mannose were compared in vitro and potential induction mechanisms of urinary AAA explored.

Results: The cranberry dietary supplement exhibited both P-type and Type 1 in vitro and ex vivo AAA, while D-mannose only prevented Type 1 adhesion. Cranberry also demonstrated more robust and consistent ex vivo urinary AAA than D-mannose over each 1-week study period at different urine collection time points. The means by which the compounds with in vitro activity in each supplement product could potentially induce the AAA in urines was discussed relative to the data.

Conclusions: Results of the current study provide consumers and healthcare professionals with additional details on the compounds and mechanisms involved in the positive, broad-spectrum AAA of cranberry against both E. coli bacterial types most important in UTIs and uncovers limitations on AAA and effectiveness of D-mannose compared to cranberry.