Abstract
Cranberries have long been purported to provide protection against urinary tract infections. There is a line of evidence suggesting that causal pathogens might be seeded from the bacteria reservoirs in the intestinal and vaginal tracts. We tested the hypothesis whether cranberry intake would reshape bacteria taxa in the gut, as well as the vaginal ecosystem. A total of 25 postmenopausal women were enrolled into a randomized, double‐blind, placebo‐controlled study. Stool samples and vaginal swabs were collected at baseline and after 15 days of consumption of placebo or cranberry beverages, microbiota analyses were performed by Illumina Miseq sequencing following a double‐index 16S rRNA gene amplicon. All baseline stool samples generally fell in the Bacteroides enterotype. Significant increases of Prevotella (P = 0.04), Clostridium XIVa members (P = 0.04), Eggerthella (P = 0.03), and Bifidobacterium (P = 0.02) were shown following the cranberry juice intervention; this indicates modulation of the gut microbiota by cranberry components. Baseline vaginal microbiotas fell in three distinct patterns—Lactobacillus dominant, diversified microbiome, and Streptococcus dysbiosis. Compared with the placebo, the cranberry intervention significantly reduced the abundance of pathogenic Streptococcus (P = 0.04) in the dysbiosis group and increased commensal bacteria Anaerococcus, Finegoldia, Actinomyces, and Corynebacterium in the diversified microbiome and dysbiosis groups. Overall, these data suggest that cranberry consumption may improve vaginal microbiota composition in individuals with dysbiosis. Gut‐borne taxa stimulation by the combination of cranberry oligosaccharides and polyphenols present in the cranberry product potentially mediates these beneficial properties.
The vaginal microbiota of post‐menopausal women can be significantly modulated by regular cranberry juice consumption (and to some extent by a polyphenol‐free placebo). Modulation may be through direct or indirect (gut microbiota) effects. The most consistent and significant modulation was a significant improvement of baseline Streptococcus dysbisosis.