Evidence Level
D-Mannose has emerged as a promising non-antibiotic approach for preventing recurrent urinary tract infections (UTIs) in women. A pivotal randomized controlled trial (RCT) by Kranjčec et al. (2014) involving 308 women compared the efficacy of 2g daily D-mannose, 50mg nitrofurantoin, and no prophylaxis over six months. The study found that D-mannose reduced UTI recurrence from 60.8% in the no-prophylaxis group to 14.6%, comparable to the 20.4% recurrence rate with nitrofurantoin, while also demonstrating significantly fewer side effects.
The mechanism of action is well-established: Uropathogenic Escherichia coli (UPEC) type 1 fimbriae, equipped with FimH adhesins, bind to mannose on bladder uroplakin proteins. Excess mannose in the urine competitively blocks this adhesion, preventing bacterial colonization. This was further supported by a pilot study by Porru et al. (2014), which confirmed similar results using 1g D-mannose three times daily.
Recent systematic reviews and meta-analyses have provided additional insights. Vargas et al. (2025) conducted a systematic review and meta-analysis of six RCTs involving 1,167 participants, concluding that D-mannose did not significantly reduce recurrent UTI incidence compared to control or antibiotics. However, Lenger et al. (2020) found that D-mannose reduced recurrent UTIs in women compared to placebo, with a relative risk of 0.23. Kyriakides et al. (2021) also reported that D-mannose reduces recurrent UTI incidence and prolongs UTI-free periods based on eight studies involving 695 participants.
In addition, Singh et al. (2026) conducted a randomized, triple-blind, placebo-controlled study demonstrating that D-mannose supplementation improved urination-related UTI symptoms and reduced symptom bother compared to placebo after three days. Riemma et al. (2025) found that combining fosfomycin with a D-mannose supplement was more effective in reducing UTI episodes than either treatment alone.
Overall, while some studies suggest limited efficacy of D-mannose compared to antibiotics or control groups, others highlight its potential