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CHICAGO — Another folk medicine remedy bites the dust. Cranberry capsules didn’t prevent or cure urinary infections in nursing home residents in a study challenging persistent unproven claims to the contrary.

The research adds to decades of conflicting evidence on whether cranberries in any form can prevent extremely common bacterial infections, especially in women. Many studies suggesting a benefit were based on weak science, but that hasn’t stopped marketers and even some health care providers from recommending cranberry juice or capsules as an inexpensive way to avoid these uncomfortable and potentially risky infections.

The new study, published online Thursday in the Journal of the American Medical Association, used rigorous methods, and the results are convincing, according to a journal editorial. Health care providers who encourage using cranberry products as a prevention method “are doing their patients a disservice,” the editorial says.


The infections

Urinary infections lead to nearly 9 million doctor visits and more than 1 million hospitalizations each year. Men, because of their urinary anatomy, are less vulnerable, while almost half of all US women will develop at least one of these infections in their lifetime. Symptoms can include painful, frequent urination, and fatigue. Antibiotics are often used to treat the infections, which usually are not serious but can lead to kidney infections and sometimes dangerous bloodstream infections. Urinary infections are the most commonly diagnosed infection in nursing home residents, but they often have no obvious symptoms, and evidence suggests antibiotics have little effect in these older patients without symptoms, the study authors say.

The study

The research included 147 older women in nursing homes who were randomly assigned to take two cranberry capsules or dummy pills for a year. The number of women with laboratory evidence of infection — bacteria and white blood cells in their urine — varied during the study but averaged about 29 percent overall in both groups. Ten infections in the cranberry group caused overt symptoms, compared with 12 in the placebo group but that difference wasn’t statistically significant. There also were no differences in hospitalizations and deaths between the two groups. The National Institutes of Health helped pay for the research, led by Dr. Manisha Juthani-Mehta, a Yale University infectious disease specialist.


The advice

People who think they have a urinary infection should see a doctor for diagnosis and treatment, but avoid cranberry products “in place of proven treatments for infections,” according to the National Institutes of Health alternative medicine branch.

The journal editorial says additional research is needed to find effective treatments for nursing home residents and others.

“It is time to move on from cranberries,” the editorial says.

— Lindsey Tanner

  • Then I can’t explain how, after being told by a urologist to take 4 cranberry capsules per day, my recurrent urinary tract infections stopped cold and I haven’t had another one in 4 years.

  • If the population studied was “147 older women in nursing homes who were randomly assigned to take two cranberry capsules or dummy pills for a year” then the most this study can claim is that cranberry capsules are not effective for older women in nursing homes following that treatment. Right?

  • I have religiously been using cranberry supplements in personal care homes for over 13 years. The effectiveness of the supplements work if they’re given prophylactically twice a day and not just once and given in the a.m. and hs times. This population is often under hydrated and incontinent therefore at night this dose matters . The majority of residents that I’ve used it with responded well and we had a reduction of UTIs up to 100% per year. One of the biggest problems with studies is collection of urine and elderly. In our population cross contamination of the urine sample is common. But rate of infection does decrease if used properly in my opinion . There was one summary written last decade which showed about a 10 hour window of effectiveness of the cranberry. When we started applying that theory in our own care home and giving one capsule twice a day we often saw big changes. I know it’s not the be-all and end-all. But we also need to look at other things like Plavix and the fact that one of the side effects of it is increased unary tract infections. I often see residence on this medication with chronic urinary tract infections. The other thing too is blood sugars and are they being controlled? The elderly population often have diabetes and these are things that we need to keep an eye on… I may not be a doctor but I am a dietician and I still feel that something is better than nothing. It’s always worth a shot

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