Cranberry Supplements

The 2023 Cochrane update included 50 studies and 8,857 participants. In women with recurrent UTIs, eight studies involving 1,555 participants suggested fewer symptomatic, culture-confirmed infections: the relative risk was 0.74, with a 95% confidence interval of 0.55–0.99.^{See reference 1}

That is a relative comparison across studies, not a promise that 26 out of every 100 users will avoid an infection. The absolute benefit depends on the starting risk. Products and study results varied, and the uncertainty interval matters when explaining the estimate.^{See reference 1}

Cranberry contains proanthocyanidins, often abbreviated PACs. One proposed mechanism is making it harder for certain bacteria to attach to the urinary tract. Processing can alter the amount present. A plausible laboratory mechanism does not tell you how well a particular capsule prevents infections.^{See reference 2}

A label may state the weight of fruit powder or extract, the amount of PACs, or both. These numbers describe different things. For example, milligrams of cranberry material cannot be read as the same number of milligrams of PACs. Check the full ingredient list and the serving size before comparing products.^{See reference 3,See reference 4}

A 24-week trial enrolled 145 women and compared cranberry products supplying 37 mg versus 2 mg of PACs daily. The higher amount did not produce a statistically clear reduction in symptomatic UTIs in the overall comparison. A favourable subgroup analysis was conducted after the main analysis and needs cautious interpretation.^{See reference 3}

This was a comparison of two defined cranberry preparations, not proof that a 37 mg label guarantees protection. Nor can its result establish that all cranberry products are ineffective. It illustrates why preparation, comparator and the preplanned overall outcome belong beside any dose claim.^{See reference 3}

The U.S. FDA permits certain qualified claims about specified cranberry products and recurrent UTIs in healthy women. Qualified means the claim must communicate limitations in the evidence. It is not the same as approving cranberry as a medicine that treats infection.^{See reference 4}

This is a U.S. labelling example, not a statement that every product sold elsewhere follows the same rules. A prominent urinary-health claim, an extract ratio or a high milligram amount should not replace checking which clinical evidence applies to that preparation.^{See reference 4,See reference 5}

Large quantities can cause stomach upset or diarrhoea. Evidence about an interaction with warfarin is conflicting, so people using it should review cranberry products with their clinician or pharmacist. Food amounts and concentrated supplements should not be assumed equivalent during pregnancy or breastfeeding; evidence for larger medicinal amounts is limited.^{See reference 2}

Bring the actual product label, including any added ingredients, to the discussion. Dietary supplements can interact with medicines, and many have not been adequately studied in pregnancy or children. A combination marketed for urinary health needs review as a complete product.^{See reference 5}