Cranberries are often touted as a home remedy for urinary tract infections (UTIs) and other bladder issues. However, a 2016 study questioned their effectiveness for this purpose. The double-blind study was published in JAMA and included 185 women, 65 years and older, living in 21 different nursing homes. For a year, the women received either a placebo or two cranberry capsules daily. The two capsules were equivalent to 20 ounces of cranberry juice and contained 72 mg of proanthocyanidins—cranberries’ active ingredient. Then, every two months, the researchers looked for the presence of bacteria and white blood cells in the women’s urine, which is considered to be an indicator of infection. The women were also monitored for symptoms of UTIs, confirmed cases of UTIs, and any changes in their health status. At the end of the study, researchers found that:
There were no statistically significant differences in urinary bacteria and white blood cells, UTI symptoms, or confirmed cases of UTIs in women taking the placebo versus the cranberry capsules.
However, a few of the study's non-statistically significant results were consistent with the possibility of cranberries' benefits. These findings included a 14% reduction in the prevalence of bacteria; a 62% reduction in the frequency of antibiotic-resistant infections by a certain type of organism; and a 23% reduction in the number of times antibiotics were used for suspected UTIs.
While considering these findings, it’s important to note that many previous studies have found that cranberries do have a beneficial effect on UTIs in women. Past clinical research suggests they may have positive effects on urinary tract health in other populations as well. For example, one study found that cranberry juice helped reduce the number of UTIs in children. Another study discovered that, in men, cranberry extract improved urinary flow and other symptoms associated with prostate-related health conditions.