Cranberry Juice and UTIs

cranberriesYou’ve known for years that cranberries can help stave off urinary tract infections (UTIs), but now scientists have figured out the mechanism behind the benefit!

In a study published in this month’s Colloids and Surfaces B: Biointerfaces, researchers from Worcester Polytechnic Institute in Massachusetts analyzed the Gibbs free energy of adhesion changes between bacteria and uroepithelial cells exposed to varying concentrations of cranberry liquids. In English? Essentially, the researchers extracted some cells from the inside of the urinary tract, threw in some bacteria, doused them with cranberry juice and watched to see how they would interact.

According to the researchers, when bacteria with fimbriae (a fancy term for hair-like projections on an organism) are exposed to even low concentrations of cranberry juice, the energy levels of the bacteria were increased to levels that made it difficult to attach to the urinary tract cell. Confused? So were we…until you consider that those hair-like projections are always present on the virulent bacteria responsible for causing UTIs and not on other, healthy bacteria.

Speaking to the mechanism behind the…uhhh…mechanism, the researchers suggest that the fact that the cranberry juice only affected bacteria with fimbriae suggests that something in the juice may directly change the molecular structure of the fimbriae themselves.

Commenting on the data, study author, Terri Camesano, notes that in the case of UTIs, “cranberry juice targets the right bacteria — those that cause disease — but has no effect on non-pathogenic organisms, suggesting that cranberry juice will not disrupt bacteria that are part of the normal flora in the gut.” In addition, Sano notes that “unpublished work also shows cranberry juice has potent effects on disease-causing bacteria, but that the effect is temporary.”

So how much juice are we talking here? Well, according to the researchers, fewer and fewer attachments were observed as the concentration of cranberry juice were increased, suggesting that in order to “realize the antibacterial benefits of cranberry, one must consume cranberry juice regularly, perhaps daily.” They do note, however, that regular cranberry juice cocktail and sugar-free cranberry juice both work equally well to reduce infections.

To keep it primal, we’d suggest adding a handful of raw cranberries to a salad (a 100g serving has 12 grams of carbs). If you’re in a rush though (or simply prone to UTIs) we’d suggest opting for a reduced sugar cranberry juice – just make sure it’s made with actual juice!

amayu Flickr Photo (CC)

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20 thoughts on “Cranberry Juice and UTIs”

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  1. That’s awesome!
    And no I had no idea that cranberries could help cure UTI. Just goes to show that science is making breakthroughs all the time.

  2. Very well explained. And I do enjoy cranberries, but unfortunately not on a daily basis.

  3. Fascinating stuff. But there is one small snag: I can not abide the taste of cranberries. Well, not unless there is rather a lot of sugar involved. Too much sugar, actually.

    So it is just not going to work for me.

    Ah well.


    1. You can use Stevia as a replacement for sugar without all the calories and it tastes like sugar. I cook with it.

  4. This info. has been around a long time. I developed a bladder infection while pregnant and didn’t want to take anti-biotics. I kept my bladder full of cranberry juice for 2 days–all better.

    I wouldn’t buy the stuff at the grocery store that is full of sugar and water. At the health food store you can find 100% cranberry juice. Mix 2-4 oz. with water to taste. Not bad at all, especially if you need it.

  5. Yes this is one of the few things that truly delivers!

    Supplemental forms of cranberries such as concentrates, extracts, and the D-Mannose sugar found in cranberries and some other fruits, also works very well. You can even find these in the grocery store now.

    Every time I get a UTI I am eternally grateful that I have this berry at my disposal.

    BTW Mark your website is wonderful.

  6. Yes, it works for UTI. Not well known, though, is it’s effect to Coumadin level. It elevates coumadin level (measured as INR in blood test) eradically, making the coumadin dangerous and its level hard to control. So, for those who take coumadin as a blood thinner for clots, stroke, atrial fibrillation, be careful. You may not find it in the books or any study just yet, but from working in 3 different nursing homes in the past, we noticed a big correlation. A few other nurses, the veteran ones, know about this as well.

  7. Ahhh, UTIs. I remember them well. Haven’t had one since I gave up starch and sugar foods and got my blood sugar in a normal range. High sugar/starch consumption and/or hyperglycemia (high blood glucose) is a underlying and often overlooked risk factor for frequent UTIs. Other risk factors (for females) include synthetic hormone contraception, tissue changes from the hormonal shifts of perimenopause and menopause, not to mention, certain, um, activities, and dehydration, etc. Staying healthy, rested, nourished, and keeping the immune system in tip-top shape (dare I say, follow the Primal Blueprint?) goes a long way toward warding off UTIs in the first place, too.

    Cranberry is great for simple, infrequent UTIs, which are usually caused by e. Coli bacteria. The bladder and urine should remain sterile and slightly acidic when healthy.

    But too often, UTIs become frequent or chronic and both sufferers and doctors continue to treat (or self-treat) without investigating to find the root of the problem – you know, it’s the weekend/holiday/you’re out of town/something inconvenient – and you call the doc, he/she calls in a Rx for everyone’s convenience, and everyone is happy, for a while. Or you self treat and sometimes it works and sometimes it doesn’t.

    Frequent or chronic UTIs can strip the interior of the bladder’s protective coating (similar to the the inside of the cheek) and set up a situation for UTI-like symptoms on a frequent or constant basis, but often without the bacterial infection. It’s called Interstitial Cystitis (when bladder cells have cell walls are “leaky”, creating irritation, inflammation, pain and muscle spasms, which feel like simple UTIs. The urine is usually already too acidic in people with Interstitial Cystitis. Chronic or frequent UTIs should be investigated and IC ruled out by a urologist (specializing in female urology if the patient is female, which is more typical).

    In the case of Interstitial Cystitis, cranberry juice will increase the urine acidity and inflame the “leaky” bladder cells even more. In this case, because the cystitis is caused by inflammation, not bacteria, making the urine less acidic with 1/4 tsp of baking soda in a glass of water a couple times a day helps a lot and calms the inflammation.

    After many UTIs between ages 20 and mid-30s (my high carb, high sugar years, too), multiple doctor abd urologist appts and tests, many Rx for Macrodantin – even a low daily dose for an entire year, and drinking cranberry juice ad nauseum, I learned about moving the urine pH the other direction after having a UTI on vacation in Dublin, Ireland. The urgent care doctor I saw told me to eat soda bread and drink the “soda” water I described above. Not much later, in an attempt to get the, um, bottom of my UTI issues, I read a book by a female urologist about Interstitial Cystitis and it made perfect sense, in that context. After that, I downed a glass of baking soda and water 2 x day at the first sign of a UTI and usually nipped it in the bud.

    I shared the book on Interstitial Cystitis with 2 women I worked with who were experiencing frequent UTIs while they were approaching menopause – the baking soda water worked for them, too.

    I haven’t even had a hint of symptoms since going low starch and low sugar four years ago.

    UTIs should never be ignored. If self-treatment doesn’t improve symptoms rapidly (in one day), or if the UTI returns or remains chronic, see a health care provider asap. An infection can move up into the kidneys and cause scarring, resulting in impaired kidney function, and no one wants that.

    FYI, I like to make Cosmopolitan cocktails with 100% (unsweetened) cranberry juice (not the same as cranberry juice “cocktail” blended with other juices – those have added concentrated fruit sugars). I also use Sogu (or Shochu) neutral distilled spirit instead of vodka because it has half the alcohol (25% or 50 proof), plus a bit of triple sec and fresh lime juice. It’s sweet-tart, but can be sweetened to taste, too.

    1. This is great information. I used to get UTIs a lot. In fact, I used to go to my doctor so much (because they would not prescribe a prescription without funning tests). My doctor just told me that bladder infections are something that I just have to live with. I was so bummed. Knowing that everytime I travel I always have to take my antibiotics with me. If I ever left them home, I always had on my mind that one was going to come.

      I started following the primal blueprint because I entered into a challenge at my crossfit gym. I never got an infection throughout the challenge.

      After the challenge was over I went on vacation and didn’t really stick to a strict diet. I was off this diet for about a month, and sure enough, I had an infection. I’m back on it and for a month I have not received one.

      I KNOW it is not a coincidence. I nailed it in the head and I’m soo happy.

    2. I have tried it all and I am so happy I found your post!! Everytime I go to the Doctor they find not bacteria in my test. I am currently between insurance. My new insurance kicks in I will be evaluated for IC in the meantime I will start a regimen of baking soda.

    3. Hi Anna, I know this post is years old but what is the book on IC you mentioned

      Thanks Lottie

  8. For all of you who cannot “abide” the taste of cranberries (love that!) or who are watching your sugar intake, which can be high in cranberry juice, there is an option. I myself cannot handle the acidity, although I enjoy the flavor. I take a concentrated cranberry capsule. Works wonders!! It works as quickly if not quicker then gallons of juice!

  9. Very interesting read…I like the mention of my Alma Mater too (Worcester Polytech aka WPI)…

    1. Anna,

      I have tried it all and I am so happy I found your post!! Everytime I go to the Doctor they find not bacteria in my test. I am currently between insurance. My new insurance kicks in I will be evaluated for IC in the meantime I will start a regimen of baking soda.

  10. I have been prone to UTI’s since I was a baby. Throughout my life I have been on a low dose preventative antibiotic. My mom would always have cranberry juice in the house and made me have a cup a day. I hated it, but still did it. I don’t think this is new information, as I was doing this in the mid 80’s. Then as a young adult I did a lot of research and tried getting of the preventative antibiotics and do the straight cranberry regime. I would try and try again, but it never would consistently hold of a UTI. I think it might work for some, but not for me.