Does Drinking Cranberry Juice Help Prevent a UTI? A Review of the Evidence.
Let’s take a quick second to talk about cranberry juice and urinary tract infections. You may have heard that cranberry juice can reduce the risk of developing a UTI, but is there any credible evidence to this commonly held belief?
Urinary tract infections are common, especially among women, and are most commonly caused by the bacteria escherichia coli or E. coli. This is a class of bacteria that is also associated with gastrointestinal disease when found in food products. They account for approximately 8 million doctors visits and 1.6$ in costs annually in the US.
Originally, researchers and physicians thought that drinking cranberry juice made your urine more acidic, thus making it a less hospitable environment for bacteria. However, when they tried to make your urine acidic with other products, they did not find the same effect. Now, there is some evidence to suggest that the cranberry juice actually helps prevent the bacteria from sticking to the walls of the urethra.
Here are a few notable studies.
One study, published in 2002 (Canadian Journal of Urology, Stothers et al) found “ cranberry juice and cranberry tablets statistically significantly decreased the number of patients experiencing at least 1 symptomatic UTI/year (to 20% and 18% respectively) compared with placebo“
Another study, published in 2001 (BMJ, Kontiokari et al) found a “20% reduction in absolute risk in the cranberry group compared with the control group.”
However, another study published in 2001 (Kirchhoff, et al) in a geriatric population and concluded “Cranberry juice in a geriatric department, where the mean stay was 4 weeks, did not influence the incidence of urinary tract infections.”
There are quite a few other studies that had positive results (i.e. it does help) or negative results (i.e. it doesnt help). Much of these differences can be attributed to (a) different dosages of cranberry juice, (b) different populations being studied (kids, adults, elderly) and (c) differences in study design.
Despite some mixed results, it does appear that cranberry juice can reduce the risk of developing UTIs, especially among women who are at high risk of developing them. There are no standardized recommendations for dosages, however somewhere between 1-10 oz/day is common.
A few caveats to that statement:
- It does not appear to be as helpful in children or elderly
- Cranberry juice may help prevent a UTI, but it does not treat them. If you suspect you have a UTI, seek medical attention.
- For some folks, drinking cranberry juice does increase the risk of kidney stones
- Can interfere with warfarin/coumadin