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A urinary tract infection (UTI) is when bacteria accumulate in the bladder and may also infect the kidneys in some cases. There has been debate over whether cranberries have the ability to impact infection rates. And new research suggests that in most individuals, cranberries can help. Cranberry juice or tablets make a subtle, but measurable difference that can protect against bacterial infections in the urinary tract! 

Common and painful:

UTIs are considered the most common bacterial infection. They are more common in women than men, with at least one in three women developing a UTI requiring antibiotics by age 24. Risk factors include: diabetes, sexual activity, spermicide or diaphragm use, pregnancy, low estrogen due to post-menopause, enlarged prostates in aging men, those with kidney stones or urinary catheters. They can also stem from genetic causes.

Infection symptoms often involve painful, frequent urination. If left untreated, this progresses to a fever and lower abdominal pain. Without antibiotics, these infections spread up through the ureters and infect the kidneys, causing vomiting and flank pain on the lower sides of the body. 

How do cranberries protect us? 

Many studies had found advantages to cranberry products, but others did not. We finally see some signs of resolution based on a 2023 meta-analysis that considered data from fifty randomized controlled trials on over 8,800 study participants. UTI rates in those taking cranberry products were compared to rates among control groups that took placebos or no treatment. The results suggest that cranberries (as juice, tablets or capsules) reduced UTIs, but no difference in UTI rates were found in the elderly, pregnant women, or those who had bladder emptying impairments. Low, medium and high doses showed no difference in protection, suggesting that even small doses may offer small advantages to avoiding UTIs.  

Importantly, cranberry products are not treatments for UTIs. Those infections often require antibiotics. Instead, cranberries may deliver fewer lifetime infections if they are regularly consumed. 

How does it work?

The active ingredients in cranberry juice that reduces risk of UTI are called proanthocyanidins. One subtype of these proanthocyanidins prevents bacteria from sticking to the walls of the urinary tract. It makes those walls more slippery by acting as an anti-adhesive. And without the ability to hang on, proanthocyanidins prevent bacteria from forming new colonies and infecting the tract. Note that these do not cure UTIs but instead, make a difference in our susceptibility.

An easy way to remember this is to envision a slip ‘n slide. “Proanthocyanidins” is not an easy word to remember, but “putting the hose on the slip ‘n slide” captures how these plant compounds work. When you eat plants that provide proanthocyanidins, you help your urinary tract stay slippery enough that bacteria cannot hang out and multiply in your bladder. Staying hydrated also ensures you’ll be using the bathroom enough to help expel any bacteria en route to the bladder. 

We get most of those proanthocyanidins through eating apples in our diet, but as you can see, cranberries provide very high amounts of these beneficial molecules.

Just how amazing are cranberries as sources of proanthocyanidins?
Check out the table of foods and the number of milligrams of proanthocyanidins per 100-gram serving: 

Can I eat more fruit and reap the same benefits? 

Unfortunately there’s little data on whether fruit alone can protect against UTIs, but research has asked a similar question when it comes to eating healthier. Yes, plant-based eating is associated with less susceptibility to bacterial infections. For example, in women, eating more fruit and veggies confers some protection from UTIs. There is also research that indicates a higher fruit and veggie consumption in older men has similar protective benefits for UTI occurrence. More research is needed, but there are so many additional benefits to eating a plant-powered diets that it’s certainly worth trying!

Of course, more fruits and veggies means you’ll be consuming more fiber and getting the nutrients that help us avoid depression, too. Hopefully these nutrition-driven results have you planning on eating more fruits and veggies to help your body function at its best.