Is Cranberry Juice Good for Your Kidneys?

You’ve no doubt heard about the potential for cranberry juice to help with some types of urinary tract infections (UTIs). But what about your kidneys? A UTI can start out in your bladder and then travel to one or both of your kidneys. If not treated properly, an infection can damage your kidneys, and the bacteria can spread to your bloodstream, potentially causing a life-threatening infection.

The first thing to know is that, yes, cranberries can protect against UTIs: They may reduce the risk of UTIs by one-third in people who are at risk for developing UTIs or who get multiple infections, according to the National Center for Complementary and Integrative Health.

How cranberry juice helps

E. coli, a bacteria that lives in your gut, is a common cause of UTIs, says Ketan Badani, professor of urology at Mount Sinai Health System in New York City. “What we know is that consuming cranberries helps prevent (E. coli) bacteria from adhering to the wall of the urinary tract.”

Cranberries pack certain antioxidant compounds called proanthocyanidins that stop bacteria from taking up residence. They’re most effective in preventing future infections in women who have recurrent UTIs—meaning, two or more confirmed UTIs within six months—notes a review of studies published in 2016 in Advances in Nutrition.

The most common type of UTI is a bladder infection, according to the National Institute of Diabetes and Digestive and Kidney Diseases. The telltale symptoms of a bladder infection are burning while peeing and peeing a lot. The go-to treatment is antibiotics.

So the question remains: If cranberry juice is good for your bladder, can it help with your kidneys? The answer seems to be that a little of the juice goes a long way: Here’s what you need to know about UTIs and whether you should drink cranberry juice for your kidneys.

(Related: 16 Prescription Drugs and Supplements You Should Never Mix)

UTIs and your kidneys

“A kidney infection can make someone very sick,” says Dr. Badani. Kidney infection symptoms include chills, fever, pain in your back, nausea and vomiting, foul-smelling urine, and frequent, painful urination.

Untreated UTIs not only have the potential to spread to the kidneys, but they can also enter the bloodstream, causing sepsis, says Michael Lutz, a urologist with Beaumont Health in West Bloomfield, Michigan. Add sepsis—the body’s life-threatening response to an infection—to the many reasons you should always seek prompt treatment for any UTI, including a kidney infection. Also know that cranberry juice is not a substitute for medical care.

Can cranberry juice treat a kidney infection?

No, cranberry juice can’t treat a kidney infection. However, just like with a bladder infection, consuming cranberry products may prevent bacteria from attaching in the kidneys, says Dr. Badani. Although there isn’t research looking at kidneys specifically, cranberry juice may help create an environment that’s less hospitable for E. coli.

(Related: 7 Innocent Mistakes That Put Your Kidneys in Trouble)

What about cranberry juice and kidney stones?

While cranberry juice, in general, is a healthy way to promote bladder and urinary health, drinking a lot can lead to kidney stones in certain people, says Dr. Badani. Kidney stones are small, hard mineral and salt deposits that form in the kidneys and tend to bind together in urine. This may cause nausea and sharp pain in the abdomen as the kidney stones pass through your urinary tract.

Consuming cranberry products may not be a safe home remedy for kidney stones because they contain oxalates. If you’re prone to kidney stones, oxalate-containing foods can contribute to their formation. What’s more, cranberry also lowers the pH of your urine. Some stones like to form in acidic urine, while others tend to dissolve more readily in it.

The problem comes in when you overdo cranberry and consume over-the-top amounts, says Dr. Badani. If you are prone to kidney stones as well as UTIs, talk to your doctor before consuming cranberry products.

(Related: What Is My Pelvic Floor and How Do I Take Care of It?)

How much cranberry juice should you drink?

If you’re going to try cranberry juice as a means of preventing recurring UTIs (and thus stopping the infection from worsening and traveling to your kidneys), there’s good news. A study published in 2016 in the American Journal of Clinical Nutrition suggests that 8 ounces of cranberry juice per day can help lower the likelihood of infection compared to a placebo.

How to find and use cranberries

There are several ways to consume cranberries: In juice, capsules, powders, or extracts. Dr. Badani prefers cranberry extracts, as they’re likely to have a higher concentration of UTI-fighting substances. Another option? Homemade cranberry juice. Just boil fresh cranberries, then strain the mixture until you have liquid.

Otherwise, pay attention to the type of cranberry juice you’re buying, and check the ingredients listed on the label. Choose one that is 100 percent cranberry juice: Note that you may need to cut it with seltzer and add some light flavouring to make it palatable. Just be sure to avoid bottled varieties that have added sugar, high fructose corn syrup, or other juice blends. These are often labeled “cranberry juice cocktail,” and typically contain more sugar and less actual cranberry than pure cranberry juice.

When to have a cranberry product

Developing a UTI is entirely normal, says Dr. Badani. “It’s possible to get a one-time infection and never get another again,” he says.

It doesn’t mean that something’s wrong with your body. Women are more likely to have recurrent UTIs because their urethra is shorter than a man’s, giving bacteria easier access to the bladder, he says. And some people may have more bacteria, and thus are more likely to get an infection.

“If you have no UTI issues, there’s no reason to go on cranberry,” says Dr. Lutz. “It won’t make a healthy urinary tract healthier. But if you’re already suffering from recurrent infections, cranberry might be a good holistic approach to make a rough situation better.”

When it comes to your kidneys specifically, the ideal patient to put on preventative cranberry is someone who has had a kidney infection already, says Dr. Badani.

“Even if we don’t have concrete evidence, this is the person I’d want to put on a prophylactic cranberry to help prevent a future infection,” he says.

Next: Should You Eat Cranberries? The Benefits, Nutrition, and More