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Cranberry

Cochrane-supported for recurrent uncomplicated UTI prevention in women, proanthocyanidin dose is what matters.

Why

Cranberry (Vaccinium macrocarpon) extracts have one of the few well-established prevention indications in herbal medicine. The 2023 Cochrane review concluded that cranberry products reduce the risk of symptomatic, culture-verified UTI in women with recurrent UTIs, in children, and in people susceptible after interventions. Effect is dose-dependent, products delivering at least 36 mg/day of proanthocyanidins are the ones with consistent positive results.

How it works

A-type proanthocyanidins inhibit P-fimbriated E. coli adherence to uroepithelial cells, the first step in colonisation and infection. Effect is dose-dependent and requires a quantified PAC content.

Expected onset · Prevention effect assessed over 6–12 months of consistent use; not for treating an established UTI

How to take

Dosage

Standardised extract delivering ≥36 mg/day proanthocyanidins (PACs), typically once or twice daily. Cranberry juice (250 ml twice daily) was used in older trials but PAC content varies widely.

Timing

Daily, divided or single dose

On the label

Products stating 'PAC content' as DMAC-quantified milligrams. 36 mg PAC/day is the dose-response threshold for the positive trials.

Ideal for

Adult women with recurrent uncomplicated UTI; children with recurrent UTI; people susceptible to UTI after urological intervention.

Safety

Caution with warfarin, INR elevation has been reported, though meta-analyses suggest the signal is small with standardised low-dose products. Avoid in those with calcium oxalate kidney stones (cranberries are high in oxalate). Pregnancy: safe at culinary doses; supplement data limited.

Evidence

At a glance

Cochrane 2023 SR (50 RCTs, n=8,857): cranberry products reduce the risk of symptomatic culture-verified UTI in women with recurrent UTI (RR 0.74) and in children. Effect concentrated in standardised products delivering quantified PAC content (≥36 mg/day) rather than juice alone, the dose-response is well documented.

Where to get it

Shop Cranberry on Amazon

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