Over the course of a woman’s lifetime, a woman has about a 50% change of developing at least one urinary tract infection (UTI) and 20-30% experience recurring UTIs. The mainstay of conventional treatment are antibiotics, which do in fact usually work quite well. However, one problem is that they can also lead to a vulnerability to another UTI because the antibiotic does eliminate the causative bacteria but also reduces the uroprotective lactobacillus species that are needed as defense for colonization of UTI microbes and a future UTI. Too frequent use of antibiotics also can have a detrimental effect on not only bladder microbiota, but gut and vaginal microbiota as well.
Cranberry extracts have a long tradition as well as a body of science for use in prevention of recurring UTIs. Not all that science shows efficacy, but studies do show the ability of cranberry extract to inhibit E. coli adherence in the bladder and E. coli is the most common cause of UTIs.
Cranberries are rich in polyphenols. This current prospective uncontrolled exploratory study evaluated the clinical effects of a cranberry supplement in women with recurrent, uncomplicated UTIs and in addition, assessed changes in the intestinal microbiome.
Women were included in the study ages 18 to 70 and had to have a history of at least three uncomplicated infections in the previous year or two infections in the last six months. They could not be using regular probiotics or probiotic yogurt and no recent history of antibiotics in the previous month. Women received three capsules of a cranberry extract supplement (Cystorenal® Cranberry Plus; Quiris Healthcare Gmbh & Co. Kg; Gütersloh, Germany) daily for six months. This product contains 300 mg of cranberry extract (including 12 mg of proanthocyanidins), 100 mg of pumpkin seed extract, 20 mg of vitamin C, and 0.47 mg of riboflavin.
The primary outcome was the change in the number of UTIs after the 6-month period of the supplement compared with the previous 6 months. Secondary outcomes included any change in the number of antibiotic therapies after 6-months compared with the prior 6 months. Quality of life was also measured using a questionnaire.
Twenty-three women were included in the study and reported 2.2 ± 0.8 UTIs at baseline looking at the previous six months. After six months of cranberry supplement intake, the patients reported 0.5 ± 0.9 UTIs. The use of antibiotic therapy was significantly reduced after six months of cranberry supplementation (1.14 vs. 0.14). Quality of life score slightly improved. Of the 23 women included, 13 had no UTIs during cranberry intake.
Commentary:
I’m not sure why they included that minimal amount of vitamin C and the tiny dose of riboflavin. More vitamin C might have had a therapeutic effect. It appears that this product, and likely largely if not only, due to the cranberry extract, taken once daily for six months reduced the number of UTIs and antibiotics used in women with recurrent uncomplicated UTIs. How cranberry works is likely more than just the one mechanism of reducing bacterial adhesion. Other possibilities include anti-inflammatory mechanisms, improving bladder and gut microbiota and possibly even an influence on biofilm formation. Other strong contenders in reducing recurrence of UTIs includes berberine and mannose and in perimenopausal and especially postmenopausal women, low dose vaginal estrogen improves the vaginal microbiota which then also influences the bladder microbiota.
Reference:
Jeitler M, Michalsen A, Schwiertz, et al. Effects of a supplement containing a cranberry extract on recurrent urinary tract infections and intestinal microbiota: A prospective, uncontrolled exploratory study. J Integr Complement Med. May 2022; 28(5):399-406.
