Can Cranberry Juice Reduce the Number of Urinary Tract Infections (UTI)?
Title: Consumption of a cranberry juice beverage lowered the number of clinical urinary tract infection episodes in women with a recent history of urinary tract infection
Author: Maki et al
Journal: American Journal of Clinical Nutrition
Objective: To assess the effects of the consumption of a cranberry beverage on episodes of clinical UTIs
It is estimated that 150 million urinary tract infections occur yearly around the world. In the US, they account for more than 6$ billion in annual costs.
Just to review the anatomy briefly, a urinary tract infection describes an infection that involves the urethra, bladder, ureters and/or kidneys. Most urinary tract infections manifest as urethritis (inflammation of the urethra) or cystitis (inflammation of the bladder), but they can ascend into the kidneys causing a more severe infection termed pyelonephritis (infection of the kidneys).
Known risk factors for a urinary tract infection include
- Female (shorter urethra)
- Sexual activity
- Catheter use
- Other (urinary tract abnormalities, blockage, immunosuppression, recent procedure)
Although rare, complications of urinary tract infections can cause damage to your kidneys, damage to developing babies in pregnant women, stricture or narrowing of the urethra and sepsis as a life threatening manifestation of the disease.
Prevention of urinary tract infections is important. Methods to do this include:
- Drinking lots of water (dilute your urine, flush out bacteria)
- Use of heating pad (warm heating pad can reduce bladder pressure/ discomfort)
- Wipe from front to back (women)
- Empty your bladder after intercourse
- Change birth control if appropriate (diaphragms, unlubricated or spermicide-treated condoms can contribute to bacterial growth)
The evidence regarding cranberry juice is mixed and the authors of this study wanted to know if it can help prevent the development of a urinary tract infection.
This was a randomized, double-blind, placebo-controlled, multicenter clinical trial that included women with a history of a recent UTI were assigned to consume one 240-mL serving of cranberry beverage per day (n = 185) or a placebo (n = 188) beverage for 24 wk.
The primary outcome was the clinical UTI incidence density, which was defined as the total number of clinical UTI events (including multiple events per subject when applicable).
The mean age was 41 years, there was 98% compliance and 86% of subjects completed the study.
There were 39 investigator-diagnosed episodes of clinical UTI in the cranberry group compared with 67 episodes in the placebo group, meaning there was roughly a 40% reduction in UTIs in the cranberry group consuming group. (antibiotic use–adjusted incidence rate ratio: 0.61; 95% CI: 0.41, 0.91; P = 0.016).
Clinical UTI with pyuria, or bacteria in the urine, was also significantly reduced (incidence rate ratio: 0.63; 95% CI: 0.40, 0.97; P = 0.037).
One clinical UTI event was prevented for every 3.2 woman-years (95% CI: 2.0, 13.1 woman-years) of the cranberry intervention.
Consumption of cranberry juice lowered the number of clinical urinary tract infections in women with a recent history of urinary tract infection.
This is probably the best study to date investigating this question and certainly supports the claim that cranberry juice helps.
As cranberry juice is a fairly benign beverage, for women at risk of UTI or with a history of UTI, consumption is a very reasonable method of reducing your risk of future UTIs.
Maki, K. C., Kaspar, K. L., & Khoo, C. (2016). Consumption of a cranberry juice beverage lowered the number of clinical urinary tract infection episodes in women with a recent history of urinary tract infection. American Journal of Clinical Nutrition, 103(6), 1434-1442. doi:10.3945/ajcn.116.130542