People who suffer from chronic urinary tract infections may want to put down the cranberry juice. The once-promising cranberry treatment is looking less and less like an alternative cure-all for UTIs, and more like a folk tale.
A recent randomized controlled trial, the highest standard of scientific evidence, found that people who took cranberry capsules didn't protect themselves from a urinary tract infection any more than people who took placebo pills.
This is disappointing for the scientists urgently looking for new cures for this common infection. While antibiotics can cure UTIs, overuse can create antibiotic resistance in bacteria that cause the infection, leading to hard-to-treat illnesses. Already, UTIs caused by antibiotic resistant bacteria have popped up on the U.S. Centers for Disease Control and Prevention's radar, and if they spread to become a serious threat, the superbugs could wreak havoc on a healthcare system that has no other way to cure these infections.
Cranberry has no effect on a person's UTI risk
Correlational studies, which are weaker kinds of scientific evidence that measure the relationship between variables and outcomes, finds that people who regularly drink cranberry juice or take cranberry capsules are less likely to get UTIs.
But that relationship doesn't stand up when tested with a randomized controlled trial, which is a way for scientists to compare the outcomes of one group who takes the medicine with a control group that takes an inert substance.
For instance, in this most recent trial, published in the journal JAMA, researchers randomly divided 185 female nursing home residents with an average age of 86 into two groups: those who swallowed two cranberry capsules every day, and those who swallowed a placebo capsule. UTIs are a common problem among older women, and are the most frequently reported infection among people in long-term care.
In total, the two cranberry capsules contained 72 milligrams of the active ingredient proanthocyanidin, or the equivalent of 20 ounces of cranberry juice. Proanthocyanidins are thought to prevent bacteria from sticking to the cells of the urinary tract.
Over the course of one year, researchers measured two things in these women's urine every two months: the presence of bacteria and the presence of pyuria, or white blood cells (pus), that would indicate an infection.
At the end of the trial, they found there were no significant differences in UTI rates between women who took the cranberry capsules and those who took the placebo.
Back to the drawing board
It's time for both doctors and the popular health media to move away from cranberry cures, wrote Dr. Lindsay E. Nicolle of the University of Manitoba in an editorial that accompanied the JAMA study.
“Any continued promotion of the use of cranberry products seems to go beyond available scientific evidence and rational reasoning,” she wrote. Nicolle also points out that this most recent study is just the latest of several studies that cast doubt on cranberry juice as a way to prevent or cure recurrent UTIs in women of all ages.
While scientists continue exploring new, non-antibiotic ways to cure recurrent UTIs, it looks like the only non-pharmaceutical weapon we have against them is prevention. That includes wiping your genitals from front to back after using the toilet, washing your genitals before and after sex, and steering clear of feminine “hygiene” products.
Bottom line: If you're a cran fan, enjoy the juice for its taste ― not its mythic urinary tract-protecting reputation.
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