Cranberry Juice for UTI: Quackery?

On Oct. 28th, the article, You Need to Stop Trying to Treat Your UTI With Cranberry Juice, was posted on Dr. Mercola's website. Dr. Mercola's team normally puts out good material, so I feel the need to correct this for the sake of anyone with urinary tract infections who uses or has considered using natural therapies (conflicting info doesn't help), and in honor of the good work that they normally do: the bad work needs to be weeded out.

Mercola's article is based on this study, published yesterday in JAMA: Effect of Cranberry Capsules on Bacteriuria Plus Pyuria Among Older Women in Nursing Homes A Randomized Clinical Trial, which I'm going to refer to in this post as Juthani-Mehta, et al. (for those unfamiliar, this is a shorthand way, using the authors' names, that the scientific community sometimes uses to refer to a study). The study, in short, is evaluating the effect of daily dosing for one year of two cranberry capsules on chronic bacterial infection of the urinary tract in the residents of a nursing home.

There are two basic problems here, with the details discussed below:

One, the researchers, by doing this trial, seem to be looking for an easy and inexpensive treatment to reduce symptoms and frequency of urinary tract infections in nursing homes, which is admirable work and worth doing. But they do not appear to be sufficiently trained in botanical medicine, including the use of cranberry, to design an effective treatment protocol.

Two, Mercola's writing team misapplied the study and blew the results out of proportion for what the science of it actually means and says.

Here are the details:

1. The dose, two cranberry capsules, is not nearly enough to have a clinical effect on most urinary tract infections.

The dose was chosen because of a pilot study that the same group had done previously in another group of elderly individuals, showing a positive response to the two capsules. Pilot studies are small studies intended to investigate an idea a little bit before throwing money, time, and other resources into an expensive, larger trial.

All the pilot study shows, as it was designed to, is that there was a partial reduction over the period of one month in the number of E. coli colonies in the urine, with an increase in the number of other bacterial species, with no assessment of UTI symptoms. The pilot states, appropriately, that more research needs to be done on the topic. The Juthani-Mehta, et al. article IS that further research, but seeing as it shows that 2 capsules is not effective at managing UTI's, that doesn't mean that cranberry is ineffective. It means that 2 cranberry capsules are not effective, at least not for this type of UTI, in this population, and/or considering other aspects of the study. This study, as studies need to be, is narrow in focus and says nothing about other types of UTI's including the most common form in the population: symptomatic, acute UTI in young women, often following sexual intercourse.

The reporting of findings from scientific articles is a deep responsibility. Extrapolating broad statements from a narrow study is inaccurate and an injustice to the researchers, the treatment, patients, and to science as a whole.

2. Capsules are not an ideal way to dose cranberry.

Many constituents of herbs break down in response to heat, light, oxygen, and time, proanthocyanidins (the chemical compound said to be responsible for the anti-UTI effects of cranberry) included. When an herb is dried and ground to be put into a capsule, there is significant exposure of light, oxygen, and potentially heat from the grinder (depends on the machinery used), and the shelf life of that herb has just dropped through the floor. Further, how long did those cranberries sit before they were ground? How long did they sit once ground? How long have they been in that bottle? Were they ever exposed to unideal heat in transit or storage? In the case of this study, it's stated that the cranberry product was tested for proanthocyanidin content, but it isn't stated when this was done or by who: by the manufacturer before encapsulation and how long ago was that? On the other extreme: by the author's own facility right before the beginning of the study? Was it the same batch of product that was acquired at the beginning and used throughout the year, losing potency the whole time? These are not trivial questions.

In purchasing product for use, brand makes a huge difference in cranberry and most other herbal products. The industry does not have sufficient enforcement of regulation to guarantee any quality of herbal products, or even whether the herb on the bottle is what's in the bottle. This, again, does not mean that herbs don't work, it means that if you don't have the training to understand these factors and choose a quality product among the sea of possibilities, your results are unpredictable.

In cranberry's case, that active ingredient is so easily broken down, that capsules are not an ideal choice. One little trick on assessing the quality of a cranberry capsule (this is not an absolute test, but can provide insight): look at the capsule. The powder on the inside should be deeply red. The proanthocyanidin is the pigment that colors cranberry; these deep red, blue, and purple pigments in fruit and vegetables are active medicinal components. If it is not, then either the cranberry powder has been cut with something else (not what you want), or the proanthocyanidins have been so broken down that it they no longer have the properties that we want: color and medicinal action.

The alternative is cranberry juice. This has been shown to be effective, but the volume needed to have the desired result is discussed in the articles as difficult to get down. I agree, especially in a nursing home population where the residents may have difficulty swallowing and a low appetite/thirst. 100% cranberry juice is pretty intense and in an acute urinary tract infection, the dose needs to be high: several cups throughout the day, or better stated: as much as the patient will tolerate: a liter or more daily until the infection is resolved, typically only 2-3 days. At this dosage, my clinical observation, and that of my colleagues, is that the symptoms of the urinary tract infection are noticeably reduced by the next time that the patient urinates, after starting the juice. I am not aware of a study that has tested 1 liter/day of 100% cranberry juice in acute UTI patients, so this is another example of more research needing to be done.

A little trick is that related species, like blueberry, have the same proanthocyanidins and the same effect, so a patient can switch it up a little by mixing in or alternating with blueberry juice, making the treatment more palatable and less monotonous.

3. Cranberry by itself is probably not a good therapy for the disease the article is studying.

This study was not broadly assessing the effects of cranberry on urinary tract infections over many demographics and types of infections, but rather, a very narrow part of the population with a particular kind of UTI: long term, chronic bacteria in the urine in a nursing home population, where it is very common.

An acute and painful UTI in a young or middle aged woman is fundamentally different than a 3 year long, pain free infection in an 80 year old, meaning that it has different causes and therefore different treatments.  In chronic low grade infections, the bacteria is not usually the root of the problem and killing it provides only temporary benefit, if any, because the underlying issue or the reason that the bacteria grows well in that place, has not been addressed, such as dehydration (common in nursing homes because of low thirst and a desire to avoid incontinence) and a resulting lack of sufficient flushing of the urinary tract on an ongoing basis to keep it free of pathogenic bacteria.

4. The rest of the treatment needs to be followed.

A key part of UTI treatment is the physical flushing of the urinary tract by drinking enough fluid. Cranberry does not kill microbes in large amounts, or at least we don't have evidence that it does. Instead, it blocks bacteria from adhering to the bladder and urethral walls. If you detach the bacteria, but don't flush it out, it will simply reattach once the amount of proanthocyanidins in the urinary tract is low.

The Juthani-Mehta, et al. article states that the exacerbation of incontinence is one reason to choose capsules over juice for patients in nursing homes. The problem with this is that, even if one managed to get very high quality capsules and dose them appropriately, if the patient is not drinking sufficient amounts of fluid, the treatment is not going to work—a point acknowledged in the discussion section of the article. And the lack of fluid intake in general in nursing homes is part of why there is a very high frequency of urinary tract infections in the first place. This could be a vicious cycle as sometimes the infection causes the incontinence, which causes the patient to not do appropriate treatment (drinking as part of the treatment), which causes the incontinence to persist, etc.

5. There was antibiotic use for suspected UTI's during the period of the study.

This is a lesser point in regards to the study, but one worth bringing up while talking about UTI treatment.

Patients on long term antibiotic treatment were excluded from the study, but some patients did have antibiotic treatment for urinary tract infections during the study (frequency and other details not defined). Even though there was no statistical difference in antibiotic use between the control and treatment groups, this throws an extra variable into the study.

Antibiotic use in urinary tract infections may increase the likelihood of developing another one. This is partly because the antibiotics kill off not only the target organism, but a number of species in the normal flora as well. When the normal flora is damaged, there are empty niches available for other bacteria to move in, and they do. Given the lack of healthy exposure to bacteria via fermented foods in the diet and interaction with natural ecosystems outdoors, and being surrounded with anti-bacterial soaps and cleaners, we are unable to repopulate ourselves with good bacteria through our standard daily routines. As a result, the same bug (over 80% of UTI's are E. coli) living in the pelvic area because of the proximity of the anus, that caused the UTI in the first place, normally kept out of the urethra and bladder by healthy flora, is even more likely to migrate back up it after antibiotic use.

Even though most of my post here is discussing the article and defending the idea of cranberry juice as a treatment, the main reason that I wrote anything at all was to counterbalance the poor article posted on

The writer cited a report of this single study: Juthani-Mehta, et al., to say that cranberry juice has no more effect on UTI’s than placebo, but the study doesn’t even use cranberry juice. They make a blanket dismissive statement about UTI’s, but the study is of a very specific population and type of UTI; AND the study itself both cites other studies that showed positive outcomes and describes valid points about how their study may inaccurately be showing no medical benefit from cranberry.

These short and false conclusions show that the writer either didn’t read the article or has a profound misunderstanding of science, clinical trials, and herbal medicine, and yet, it was posted on a very well known medical information site, and spread via social media, with 800 hits in just a few hours. This is a caution and a reminder to know your source, even checking the original source yourself when able, and to be careful about sound bite medical information online.

The material above is not meant to be taken as medical advice, nor is the information here complete enough by itself to make accurate or wise treatment decisions. Even an increased water intake is dangerous in the wrong person. Please talk with an appropriately trained healthcare provider before treating UTI's at home.