Can Cranberry Juice Prevent UTIs? Probably Not, But an Ingredient in Cranberries May Be Helpful

Here's why you might want to consider dietary supplements instead.

Making an emergency run to the grocery store to stock up on cranberry juice at the first sign of a urinary tract infection (UTI) has become practically a ritual for women prone to this common health issue. The beverage has long been considered a home remedy for warding off these annoying infections, which, per the American Urological Association (AUA), happen to up to 60% of women at some point in their lives.

But does cranberry juice actually prevent a UTI?

There's little high-quality research, overall, on the effectiveness of cranberry products on UTIs, says the National Center for Complementary and Integrative Health (NCCIH). And what evidence exists on cranberry juice, in particular, for reducing the risk of recurrent UTIs is "limited and inconsistent," per the US Food and Drug Administration.

Even if the juice itself doesn't prove preventative, you may not want to write off cranberries for UTIs just yet. Here's why.

Can Cranberry Juice Actually Prevent UTIs? , Red Fruit Juice Pouring in a Drinking Glass
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Cranberry for preventing UTIs

If you've stockpiled an arsenal of cranberry juice to battle UTIs, there's bad news: The tart elixir probably isn't helping as much as you'd hope.

A review of 24 studies, updated in 2012 and published by the Cochrane Database of Systematic Reviews, looked at whether cranberries could prevent UTIs. Cranberry juice didn't seem to make a statistically significant impact on reducing cases of UTI.

With that said, there may be some truth to the idea that cranberries can prevent UTIs. It has to do with a substance inside the fruit called proanthocyanidin (PAC).

"PAC prevents bacteria from sticking to the lining of the bladder," Courtenay Moore, MD, urologist at The Ohio State University Wexner Medical Center, tells Health. "It creates a slippery coating in the urothelium [a thin tissue that lines the lower urinary tract], so you just pee out the bacteria."

The theory, according to a study in the journal Phytochemistry, is that PAC makes it more difficult for the bacteria to stick around long enough for form a full-blown infection in your bladder or other spots in your urinary tract. That may explain why three small studies in the Cochrane review found that cranberry products were about as effective at reducing these infections as the low-dose antibiotics doctors prescribe some UTI-prone women for prevention.

The key word in those findings, however, was cranberry products (like supplements)—not cranberry juice. The beverage itself isn't considered to be as effective because it doesn't usually have enough PAC to make a major difference, explains Dr. Moore.

"You'd have to drink 2 liters of cranberry juice a day to have enough of the active ingredient to be beneficial," she says.

And since lots of cranberry juice drinks are loaded with added sugar to offset their tart flavor, that can lead to some not-so-great effects on your overall health and nutrition.

Rather than trying to sip your way to fewer UTIs, you may want to consider taking a cranberry supplement, instead. They're packed with a specific amount of PAC, so you know exactly how much you're getting.

Like the juice, cranberry supplements have mixed evidence in their ability to prevent UTIs. A 2017 systematic review in the Journal of Urology found that cranberry products significantly lowered the rates of UTIs. But more specific studies on UTI-prone people, like older adults, nursing home residents, and those with spinal cord injuries that make bladder control difficult, found that cranberry supplement didn't make a difference in infection rates.

More research is needed to figure out whether cranberry supplements actually prevent UTIs in most women. But since there's no evidence that these tablets cause harm—and there's a potential that they may indeed help—they might be worth a try, especially if you frequently come down with UTIs, experts say.

"I have plenty of patients who will load up on cranberry supplements around sexual activity, and for some women, that's enough to prevent a UTI," says Karyn Eilber, MD, urologist who teaches at Cedars Sinai Hospital in Los Angeles, and founder and chief executive officer of lube-maker Glissant.

Dr. Moore says she recommends cranberry supplements. "There are no downsides to taking it. There's no gastrointestinal toxicity and no risk of [developing bacterial] resistance," she tells Health. "If we can prevent infections using supplements, it can help reserve antibiotics for actual treatment."

How to choose a cranberry supplement for UTI prevention

Thinking of trying cranberry supplements for a UTI? Check in with your doctor first. While cranberry tablets probably won't hurt you, it's always a good idea to talk with a medical professional before trying any new supplement.

If you're taking the blood thinner warfarin, for instance, you may want to avoid cranberry products, per the Cleveland Clinic. While NCCIH notes the evidence is conflicting, the concern is that cranberry may boost warfarin's anti-coagulation effects, leading more bruising or bleeding.

You can find a number of cranberry products at the drugstore, but not all supplements are created equal. Dietary supplements have far less regulation than, say, pharmaceutical medications, and what's stated on their packaging may not be what's actually inside the pills. In fact, a 2018 study in JAMA Network Open revealed that a whopping 776 dietary supplements contained unapproved ingredients, so you'll want to do your homework to make sure you're getting a decent cranberry tablet for UTIs (or any other kind of supplement you're thinking of taking).

"People should look for a high-quality supplement that has some sort of certification, like the USP Verified Mark or NSF certification," Bruce Sloane, MD, urologist at Philadelphia Urology Associates, tells Health. "That means it's been sent to an independent lab that has verified that what the companies have said is in the supplement is actually in the supplement." Note: If a supplement has been verified by a third-party lab, it will usually promote it on its label.

You should also check how much PAC the product contains. Clinical trials have shown that cranberry pills need to have at least 36 milligrams of PAC to reduce UTIs, per the American Journal of Obstetrics & Gynecology.

Lots of cranberry supplements contain a combination of other ingredients that may potentially boost their ability to fight UTIs. One common one is D-mannose, a simple sugar that's similar to glucose. A small study in the Journal of Clinical Urology has shown that D-mannose may help prevent (and even treat) UTIs.

Keep in mind that ingredients in some supplements can cause unwanted side effects, so talk with your doctor to see if a cranberry tablet with some of these extra substances is the right move for you.

Can cranberry juice treat a UTI?

Once you've got an infection, there's no proof that it can clear things up. Per NCCIH, cranberry has not been show to treat an existing UTI.

In fact, chugging cranberry juice may even cause some harm, says Dr. Eilber.

"Once you have a bladder infection, the acidity from the cranberry can make things worse," she explains. "If you are taking cranberry supplements when you have a UTI and you're getting worse, stop. It's time to get your urine checked to see if you need antibiotics."

Plus, some people may want to take a pass on cranberry juice for health reasons. This includes individuals with interstitial cystitis, a painful bladder condition. Cranberry juice can trigger a flare, says the Interstitial Cystitis Association.

Your doctor will ask you about your symptoms and, if it seems like you have a UTI, you'll likely be asked for a urine sample and probably start on some antibiotics. When the lab results come back, you may need to switch to different antibiotics that are better at dealing with the bacteria (assuming the ones you're already taking aren't cutting it).

The good news is that those horrible UTI symptoms (the burning pee, the frequent urge to run to the restroom) will start going away just a day or two after you get on the right medication. Just be sure to keep taking the full course of antibiotics as prescribed—otherwise you could create a strain of antibiotic-resistant bacteria that's even harder to treat.

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