Can Cranberry Juice Treat Bladder Infections?

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Cranberries may reduce the recurrence of urinary tract infections, but their role in treating infections is limited.

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Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

How could any bacteria cause a bladder infection without just getting flushed away, literally? Certainly, if you’re not drinking enough, or men who have prostate enlargement and can’t empty completely, leaving behind a stagnant pool. But, in most people, there should be a constant flow of water through there. Well, bladder infection-causing E. coli evolved these finger-like projections that they use to stick to the walls of the bladder, so they don’t get washed away. 

Almost 30 years ago now, it was demonstrated that if you drip cranberry juice on E. coli, they don’t stick as well. Grape juice doesn’t work, nor does orange or apple juice, or even white cranberry juice made from unripened berries. So, maybe it’s one of the red phytonutrients that’s doing it.

Even if it works in a petri dish, though, we don’t pee cranberry juice. I mean, how do we know that the anti-adherence phytonutrients in cranberries are even absorbed through the gut, so they make it into the bladder? Well, subsequent studies showed that if you drip urine of someone who drank cranberry juice onto E. coli, you get the same anti-stick effect. Ah, well, now we’re getting somewhere.

Here’s the stickiness of strains of E. coli wading in urine from someone drinking water, and here’s their stickiness in the urine of someone drinking cranberry juice. Within hours of consumption, there’s a drop in E. coli stickiness that appears to last throughout much of the day. So, might cranberries really help prevent bladder infections?

Well, the best way to prevent infections is to not get infected in the first place— which may involve the avoidance of chicken, as I’ve already discussed, so you’re not constantly reinfecting yourself. But, if that doesn’t work, if your gut remains stubbornly colonized with these bad bladder bugs, various tested cranberry products appear to reduce the recurrence of bladder infections by about 35%. Not as effective as antibiotics, but cranberries don’t foster antibiotic resistance, and have fewer side effects.

There’s good evidence to suggest that cranberries are effective for prevention, but not as an effective treatment; that makes sense, right? Cranberries prevent the initial adherence, but, that occurs at the start of the infection. When the infection is present, it’s already stuck there. Then, there’s no clinical data to suggest that cranberries are effective in the treatment of urinary tract infections—meaning cranberries don’t work better than placebo. But, placebos work! For example, ibuprofen seems to work just as good as antibiotics for the treatment of uncomplicated urinary tract infections.

Now, some people you really do need to treat with antibiotics—pregnant women, children, men, those with kidney infections, systemic symptoms like nausea and vomiting. But, for most healthy women, bladder infections just go away on their own, without antibiotics.

So, all the women who drink cranberry juice and have their symptoms disappear may falsely attribute their recovery to the juice. But, when it comes to most UTIs, nothing works! Nothing, in fact, actually works—leading doctors to try to figure out how they can harness the placebo effect for themselves.

Please consider volunteering to help out on the site.

Image thanks to The Atlantic

Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.

How could any bacteria cause a bladder infection without just getting flushed away, literally? Certainly, if you’re not drinking enough, or men who have prostate enlargement and can’t empty completely, leaving behind a stagnant pool. But, in most people, there should be a constant flow of water through there. Well, bladder infection-causing E. coli evolved these finger-like projections that they use to stick to the walls of the bladder, so they don’t get washed away. 

Almost 30 years ago now, it was demonstrated that if you drip cranberry juice on E. coli, they don’t stick as well. Grape juice doesn’t work, nor does orange or apple juice, or even white cranberry juice made from unripened berries. So, maybe it’s one of the red phytonutrients that’s doing it.

Even if it works in a petri dish, though, we don’t pee cranberry juice. I mean, how do we know that the anti-adherence phytonutrients in cranberries are even absorbed through the gut, so they make it into the bladder? Well, subsequent studies showed that if you drip urine of someone who drank cranberry juice onto E. coli, you get the same anti-stick effect. Ah, well, now we’re getting somewhere.

Here’s the stickiness of strains of E. coli wading in urine from someone drinking water, and here’s their stickiness in the urine of someone drinking cranberry juice. Within hours of consumption, there’s a drop in E. coli stickiness that appears to last throughout much of the day. So, might cranberries really help prevent bladder infections?

Well, the best way to prevent infections is to not get infected in the first place— which may involve the avoidance of chicken, as I’ve already discussed, so you’re not constantly reinfecting yourself. But, if that doesn’t work, if your gut remains stubbornly colonized with these bad bladder bugs, various tested cranberry products appear to reduce the recurrence of bladder infections by about 35%. Not as effective as antibiotics, but cranberries don’t foster antibiotic resistance, and have fewer side effects.

There’s good evidence to suggest that cranberries are effective for prevention, but not as an effective treatment; that makes sense, right? Cranberries prevent the initial adherence, but, that occurs at the start of the infection. When the infection is present, it’s already stuck there. Then, there’s no clinical data to suggest that cranberries are effective in the treatment of urinary tract infections—meaning cranberries don’t work better than placebo. But, placebos work! For example, ibuprofen seems to work just as good as antibiotics for the treatment of uncomplicated urinary tract infections.

Now, some people you really do need to treat with antibiotics—pregnant women, children, men, those with kidney infections, systemic symptoms like nausea and vomiting. But, for most healthy women, bladder infections just go away on their own, without antibiotics.

So, all the women who drink cranberry juice and have their symptoms disappear may falsely attribute their recovery to the juice. But, when it comes to most UTIs, nothing works! Nothing, in fact, actually works—leading doctors to try to figure out how they can harness the placebo effect for themselves.

Please consider volunteering to help out on the site.

Image thanks to The Atlantic

Doctor's Note

The reference to poultry as the source of bladder-infecting E. coli is from Avoiding Chicken to Avoid Bladder Infections, and more recently, in Urinary Tract Infections from Eating Chicken. 

What else can cranberries do? Check out Which Fruit Fights Cancer Better? and Cranberries vs. Cancer.

How can you consume cranberries palatably? Check out my recipe for Pink Juice with Green Foam.

I find it so fascinating that the white berries don’t have same effect. For more on these elusive phytonutrients, see Phytochemicals: The Nutrition Facts Missing from the Label. And, for those doubting the power of plants, see Power Plants.

I discuss the controversy around doctors giving placebos in The Lie that Heals: Should Doctors Give Placebos?

If cranberries are so good at keeping bacteria from sticking to the wall of the bladder, what about keeping bacteria from sticking to other places, like our teeth? That’s the subject of Childhood Tea Drinking May Increase Fluorosis Risk.

For further context, check out my associated blog posts: Does Cranberry Juice Work Against Bladder Infections? and Tea & Flouride Risk.

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