A new study published in the American Journal of Clinical Nutrition suggests that consuming whole cranberry fruit powder via capsule reduces urinary tract infection (UTI) risk by about half.
The research group out of Australia recruited women with a history of recurrent UTI, defined as ≥3 UTIs in the last year or at least 2 UTIs in the last 6-months. 150 women were recruited and then randomized to receive either 500 mg of the whole cranberry powder* or placebo. Over the next 6-months across 5 different study sites in the area, the incidence of culture-confirmed UTI was assessed, e.g. the researchers only counted it as a UTI if the patient was symptomatic and had bacteria in their urine sample. The most common bacteria is E. coli, which binds to the cells of the urinary tract as part of its pathogenic process. The proanthocyanidins in cranberries is thought to reduce this binding, though other aspects of the whole fruit may play a larger role.
Through 6-months, there were 38 culture-confirmed UTI’s, 25 in the placebo group and 13 in the cranberry powder group. Those taking the supplement clearly had a much lower risk of culture-confirmed UTI, which persisted after correcting for age, sexual activity, and previous UTI history. On the other hand, both groups had roughly the same amount of symptomatic UTI cases (with or without culture confirmation). This speaks to the complexity of study design, as diagnosing “suspected symptomatic UTI” does not have an agreed upon set of criteria, which can lead to differences in diagnosis.
For females with recurrent cystitis, we suggest cranberry products as an antibiotic-sparing strategy to reduce the risk of recurrence. The optimal formulation and dose are unknown, and there is no standardization across formulations in the amount of the potentially active ingredients. Acknowledging these limitations, we typically suggest an 8-ounce (approximately 240 mL) glass of cranberry juice once or twice daily or cranberry concentrate tablets 500 mg to 1000 mg total daily dose.
While cranberry juice in any form CANNOT TREAT A UTI, the clinical evidence on cranberry products and UTI is pretty good. A recent meta-analysis from Cochrane found the same effect (a reduction in UTI incidence) across 26 trials in women without other underlying urologic issues. There’s no standardized dose or product that’s recommended, but a daily glass of no-sugar added cranberry juice or a 3rd party tested supplement of ~ 500 mg cranberry powder is often recommended.
Not my typical morning read, but I thought some might find this interesting!
*The supplement was standardized to > 1.5% proanthocyanidins. We employ a similar process in our PeriRx betaine anhydrous/TMG ingredient to ensure it has enough betalains in it.