Cranberry Juice: Does It Really Help Prevent Urinary Tract Infections (UTIs)?

This is a very common question I get from my female patients, both young and old. Many seem convinced that cranberry juice or pills can stop a urinary tract infection (UTI) in its tracks when they feel it coming on, or take cranberry to prevent them. Well…they may not be wrong.

After many years of grandma’s advice, in 1994 a study was done on elderly women who consumed 300 ml of cranberry juice for three months and showed less bacterial counts in the urine. This is where the whole cranberry-UTI link picked up some steam. But there is more…

I used to tell patients that cranberry juice or pills can improve the acidity of the urine, and acid is a natural defense against bacteria. Common sense would dictate that more acid is better, and cranberries are a good source. Correct? Cranberry juice however may contain a lot of sugar, and it may require drinking A LOT of it to get the effect. This isn’t necessarily good for diabetics or those watching their weight. Cranberry pills may be helpful, but how many should you take to get the desired effect?

Not too long ago, a well designed study showed a trend, but no significant improvement in preventing UTIs with cranberry, and cranberry products, however, have not been shown to significantly reduce acidity. So now what?

Cranberry is seen as a natural element people can take, in order to prevent over consuming antibiotics. Antibiotics help, but they must be tailored to the infection, and be given at the right dose, for enough period of time to prevent recurrence, persistence or development of resistance by the bacteria. However, there are women who are most susceptible to bacterial adherence, and certain bacteria are more likely to stick to the body surfaces than others.

So, what’s so special about cranberries?

In raw cranberries there are at least six chemical compounds that can interfere with bacterial adherence to the body. These compounds modify the surface properties of the bacteria to make them less sticky to the lining of the bladder. When someone consumes cranberries, the bacteria itself are actually altered by the cranberry products that dwell in the urine, changing how the bacteria express certain proteins on their surfaces leading it to cling less effectively to the bladder. This is how cranberries reduce infection. If the bacteria are less sticky, then the bladder is more capable of washing out the bugs with good urine flow. Drinking more fluids helps to create a better flow.

Interestingly, once the bacteria are removed from exposure to cranberries, they regain their “old ways” and their adhesive properties return. A recent study showed that just 6 hours of exposure to cranberry products resulted in an 84% decrease in bacterial attachment to bladder cells. Continuous exposure resulted in the continued inability of the bacteria to attach!

Now everybody go out and get some Ocean Spray!!!

Center for Urological Services, P.C.
4545 E. Chandler Blvd, Suite 300
Phoenix (Ahwatukee), AZ 85048

480-961-2325 fax


Sub specialty in: Female Urology, Prolapse and Voiding Dysfunction