D-Mannose
A simple sugar that prevents E. coli from sticking to the bladder wall. One of the most effective non-antibiotic interventions for recurrent UTIs.
Multiple RCTs support D-mannose for preventing recurrent UTIs in women — Kranjčec et al. showed comparable efficacy to nitrofurantoin with fewer side effects. Effects: hours for binding, days-weeks for symptom resolution.
D-mannose is a simple monosaccharide that's poorly absorbed by the body — most of it passes through and is excreted in urine. Once in the bladder, it binds to FimH receptors on E. coli bacteria (the cause of ~85% of UTIs), preventing them from attaching to bladder wall cells. Without adhesion, bacteria simply wash out with urination. RCTs support its use for UTI prevention in women with recurrent infection — comparable in some trials to long-term low-dose antibiotic prophylaxis, without the resistance or microbiome costs.
- Form
- D-mannose powder or capsules. Powder dissolves easily in water. Often combined with cranberry extract.
- Dose
- Prevention: 2 g/day. Acute UTI (alongside or after antibiotics): 2 g every 2–3 hours for the first 1–2 days, then 2 g 3x daily for 3–5 days.
- Timing
- With water, anytime. Don't combine with high-glucose meals (mannose absorption rises with sweet meals).
- Schedule
- Daily for prevention in women with recurrent UTIs. As-needed for acute treatment.
- Side effects
- Generally very well-tolerated. Mild GI upset, loose stool at very high doses. Theoretical: blood sugar effects in diabetics (small portion is absorbed).
- Interactions
- Generally clean. Diabetics: monitor blood sugar at high doses.
- Contraindications
- Diabetes (relative — small absorbed fraction may modestly raise glucose). Pregnancy — safe but limited high-dose data.
- Lab markers
- Not standard. UTI symptom tracking. Urine culture if symptoms persist.
- Food sources
- Cranberries, blueberries, apples, oranges, peaches, broccoli, green beans. Food amounts are too small for therapeutic effect.
Pairs with
Cranberry extract (different mechanism — also anti-adhesion; additive). Probiotics with L. crispatus / L. rhamnosus (vaginal flora support).
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