Cranberry researchers dispute Cochrane review's findings on UTIs
“As far as I’m concerned and the other researchers (in the field) are concerned, it is a done deal,” Amy Howell, PhD, of Rutgers University in New Jersey told NutraIngredients-USA. Howell has worked on cranberry research for more than twenty years.
“There is a wealth of research from institutions globally that have demonstrated that regular consumption of cranberry juice helps promote a healthy urinary tract system,” said Christina Khoo, PhD, senior research scientist for Ocean Spray Cranberries.
The review by the Cochrane Collaboration is an update of a review first conducted in 1998 and updated in 2008. The most recent version concluded that cranberry juice does not on the whole prevent UTIs and that many studies showed a significant dropout rate, meaning juice might not be an appropriate delivery vehicle. It wrapped up by saying no further research into cranberry juice was warranted.
“We recommend no further trials with the juice be done as it’s probably not effective,” said lead author Ruth Jepson, of the University of Stirling, UK.
"What we have to do is to put this Cochrane review into perspective. It is simply a snapshot that looks at certain studies,” and not the totality of research in the ingredient, Howell said.
Cochrane's institutional shortcomings
Further, she said, Cochrane is not necessarily an authoritative voice when it comes to evaluating the state of nutrition research.
“At Cochrane they typically review pharmaceutical drug studies and their prevention of disease. They do not have anyone on their staff that specializes in supplements and functional food products. This is not their strong point,” Howell said.
A European commentary in 2005 had already cited problems with Cochrane review of nutrition studies. That review, Howell said, found that, “you really cannot really use drug criteria to review these types of foods. It just doesn’t work. You can’t look at just one thing.”
Howell quoted the European review as saying: “It’s hard to even imagine a human clinical trial in which one half of a large group of middle age people agreed to avoid vegetables for five years and then agreed to be followed up to see how many developed of them developed cancer.”
Cranberry products come in many different forms, Howell noted. They are available in juice forms, powders, extracts and so forth, and there is a mountain of research data pertaining to all of these. The Cochrane review looked just at juice products, and the fact that the ingredient studied was called “cranberry juice” seems to be the only unifying factor in the studies, she said.
“These trials (included in the Cochrane review) used all kinds of different products at different dosages. Many of these products were not standardized,” she said.
Not single compound drugs
“Cranberries are not single compound drugs, so we should expect some variation in study results as the innate complexities of nutrient actions and interactions cannot always be adequately addressed through any single research study due to this heterogeneity,” Khoo said.
“For them to say ‘No more research,’ is very damning and it’s unjustifiable based on what they did in this review,” Howell said. “I find it quite over the top.”
“The recent review on cranberry needs to be put into perspective and weighed against the other positive clinical trials over the past couple of decades, in which cranberry was effective in maintaining urinary tract health,” Khoo said.
“Recent publications show as much as a 65% reduction in UTIs, leading to reduced use of antibiotics and reduction in the number of incidences of recurrent UTI in different populations, such as children (Salo 2011, Afshar 2012) and women over 50 (Takahashi 2012). Additional research should be conducted to further explore the role of cranberry in helping reducing recurrent urinary tract infections,” she said.