A recent Yale study hopes to put to rest a long-standing myth about consuming cranberries to treat urinary tract infection.
The research team, led by Yale School of Medicine professor Manisha Juthani-Mehta, found no significant difference between the number of patients with symptoms of UTI who had consumed cranberry capsules and those who were in a placebo group and had not. The study has generated controversy within the cranberry industry since its publication, with representatives calling into question the validity of the research.
The Cranberry Institute, a nonprofit organization funded by 13 cranberry product manufacturers, including Ocean Spray, published a statement in response to the Journal of the American Medical Association article describing the study as “misleading and [suffering] from fatal flaws.” The organization pointed to the researchers’ decision to study prevention rather than treatment of recurrent UTI.
The study was published in JAMA on Oct. 27 and tracked 185 elderly women living in nursing homes over the course of a year, half of whom took two cranberry capsules a day with the equivalent cranberry dosage of a 20-ounce juice cocktail. The other half of the group took a placebo.
There is a widely circulated myth that cranberry products can help prevent and treat UTI. Of 35 female Yale students polled, 17 said they believed cranberries could help prevent or treat UTI and 27 said they had heard, read or seen information to this effect.
Every two months, patients were screened and their urine tested for the presence of white blood cells as well as the bacteria pyuria, both of which are present in UTI.
A JAMA editorial accompanying the research noted that a strength of the Yale study was its use of an objective criteria for determining probable UTI. More than half of women will contract a UTI at least once in their lives, according to the National Institutes of Health.
“For older women who live in nursing homes, I do not feel that cranberry capsules are effective at reducing bacteria or white blood cells in urine, and I don’t think they are a good strategy for a UTI,” Juthani-Mehta said.
Juthani-Mehta said she conceived of the study as a way to evaluate a low-morbidity and well-tolerated potential treatment option for elderly women with UTI.
UTI, especially in an elderly population, is notoriously difficult to diagnose, Juthani-Mehta said. Following a stringent definition of the disease would have yielded just 22 patients of the 185 with unambiguous UTI in the one-year span, she said, requiring an unfeasibly large sample size.
“We screened over 5,000 patients in 21 nursing homes, but we might have needed 500 nursing homes with thousands and thousands of patients to be able to show a difference,” Juthani-Mehta said. The study cost 3 million taxpayer dollars, but it could have cost upwards of $100 million to conduct a study where the primary outcome was stringently diagnosed UTI, she added.
The myth that cranberries can treat and prevent UTI may have been perpetuated for so long because of how ingrained cranberry products are in American culture, Juthani-Mehta said.
On its website, AZO, a prominent medicinal cranberry manufacturer, lists consuming its cranberry caplets, softgels and gummies as a way to prevent against UTI. And representatives from the cranberry industry have sharply criticized the research.
But while Juthani-Mehta believes it is fair to question the generalizability of the study based on its use of an elderly population, “What I’m not fine with is saying that either the investigation or the journal or the study were done incorrectly,” he said. “They were not done incorrectly, they were done the way we outlined. We just didn’t get the result that they liked.”
The study has received wide recognition both within and outside the scientific community, having been reported on by The New York Times, The Huffington Post and Time Magazine.
Juthani-Mehta said she was surprised by the amount of attention the study garnered from the media. However, some of the recognition has extrapolated her conclusions too far, she said.
When asked whether cranberries prevented or treated UTI, Kelly Vesty, a spokeswoman for Ocean Spray, provided links to both the Cranberry Institute and an internal Ocean Spray website that published a blog post entitled “Cranberry Juice DOES Work” in response to the Yale study. The post argued that the study used pills, not juice, and therefore could not overturn “more than 50 years of research” that proves “cranberry juice is beneficial in helping to prevent urinary tract infections.”
Juthani-Mehta said she was pleased with public interest in the study since her fundamental goal was to help people.
“Although this was a negative study — we didn’t identify a way to help people — I’m also hoping people don’t waste their money on something where I’m not convinced it will actually help them,” she said.
Future experiments might include attempting to replicate these results in a population of young women, Juthani-Mehta said, although she added that she will likely not conduct these studies because they are expensive and time-consuming.
Urinary tract infections are the second-most prevalent infection nationally, causing 8.1 million visits to health care providers per years, according to the National Institutes of Health.