D-Mannose
D-mannose is a simple sugar related to glucose, found in small amounts in fruits such as cranberries and apples. It is mostly studied for urinary tract infections.
What it is studied for
The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.
Why study this sugar?
D-mannose is a naturally occurring sugar. The proposed mechanism is to stop bacteria attaching to the urinary tract lining, allowing them to leave in urine. That rationale has not translated into a reliable preventive benefit in pooled trials. 1
Why people take it
SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.
Questions people ask
Is the proposed mechanism disproven?
No. A plausible anti-adhesion mechanism and a clinically useful preventive effect are different questions; the 2025 review found no significant preventive benefit. 1
Can it replace treatment for an active infection?
The prevention trials reviewed here do not establish treatment of an active infection. 1