Cranberry, Vaccinium macrocarpon, has been cited for at least ten years in the successive recommendations of the French -language infectious pathology (SPILF) in the prevention of recurrent cystitis at E. coli, at the 36 mg dose per day of proanthocyanidine. The National Agency for Food, Environmental and Labor Health Safety (ANSES) judged in 2011 that the available clinical data did not conclude a preventive effect in the occurrence of cystitis. This was also confirmed by a Cochrane review in 2012, compiling 24 studies carried out on 4,473 participants. In 2023, an update of this review this time joined 50 randomized clinical trials devoted to juice and/or solid forms of cranberry (with 8,857 participants, including 45 tests conducted versus placebo or a lack of treatment), and concluded that a benefit of the plant … at least in certain categories of population. Overall, cranberry would seem to reduce (with a moderate level of evidence) by 30 % the risk of recurrent urinary tract infections versus placebo or a lack of treatment after taking durations ranging from 4 weeks to 12 months. Sub-group analyzes show effectiveness in women and children suffering from recurring urinary tract infections, as well as in people prone to urinary tract infections as a result of intervention such as radiotherapy of the bladder. On the other hand, few or no differences have appeared in the elderly in institutions, pregnant women or patients with a dysfunction of bladder emptying. Given the heterogeneity of the forms and dosages tested, it is not possible to determine whether the effectiveness of the juices (generally advised at the rate of 200 ml of “pure juice” morning and evening) differs from that of solid forms.
Sources: “Cranberries for Preventing Urinary Tract Infections”, Cochrane Review, 2012 and 2023; “Crannium and urinary infections: state of scientific knowledge”, ANSES, 2011.
