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Cranberry Juice, Not Supplements Better for Urinary Tract Infections


The “secret” behind the ability of the cranberry to help prevent urinary tract infections is in the juice and not the extract in supplement form, according to a new study. Worcester Polytechnic Institute (WPI) researchers say the proanthocyanidins (PACs) found in cranberries are not the powerhouse they were believed to be, although PACs are still a factor.

New information about cranberry juice comes to light

Cranberry has a reputation as being an effective natural remedy to prevent urinary tract infections. Much of the research has focused on PACs, a type of flavonoids in cranberries, that have been shown to prevent bacteria (mainly Escherichia coli) from adhering to the walls of the urinary tract, which in turn helps prevent urinary tract infections.

Although cranberries are not the only food that contains PACs (e.g., apples, green tea, grapes are other sources), they have a different type of PAC called A-type, which are not found in other foods. These special PACs are believed to have the ability to prevent bacteria from sticking to the urinary tract walls, which can result in infection.

One of the more recent studies reported that cranberry powder standardized to 72 mg proanthocyanidins per day was sufficient to prevent the bacteria from attaching to the intestinal walls. But what about cranberry juice? Is it as effective as PACs in preventing the formation of biofilm, which is the precursor of infection?

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This question was explored in a new study, and according to senior author Terri Camesano, professor of chemical engineering at WPI, “What we have shown is that cranberry juice’s ability to prevent biofilms is more complex than we may have originally thought.” Basically, the researchers found that PACs “aren’t the silver bullet” when it comes to preventing urinary tract infections.

To arrive at this conclusion, the scientists incubated two different strains of E. coli in two different off-the-shelf cranberry juice cocktail beverages as well as separately in the presence of PACs but without juice. Biofilm did not form in the juice cultures, while the PACs demonstrated only a limited ability to reduce the formation of biofilm, and only after they were exposed to the bacteria for an extended period.

Previously, Camesano’s lab had discovered that exposing E. coli to cranberry juice caused the hook-like structures on the bacteria to curl up, making it difficult for them to attach to urinary tract cells and lead to the formation of biofilm. Now, this new finding supports the benefits of cranberry juice when compared with PACs alone.

Cranberry appears to still be a good choice for preventing urinary tract infections. However, this study indicates that “cranberry juice is better at inhibiting biofilm formation than isolated A-type cranberry flavonoids and PACs, although the reasons for this are not yet clear.”

Howell AB et al. BMC Infectious Diseases 2010 Apr 14; 10(1): 94
Worcester Polytechnic Institute

Picture credit: Wikimedia Commons



Do the researchers make recommendations as to how much juice one needs to drink to help prevent UTIs?
They do not have any idea as they did not test urine. They did petri dish studies. They placed cranberry juice (what kind, we do not know) directly on E.coli bacteria in a petri dish. When cranberry juice is consumed, it is metabolized and never touches the E.coli bacteria in its pure form. Ocean Spray proved years ago in their studies that a 10 ounce class of pure cranberry juice (33% pure cranberry extract & 66% water not the sugary blends found in the grocery) contain 36mg of bioactive (derived from juice) PAC. The 10 ounces must be consumed within 15 minutes on a daily basis in order to prevent UTIs. I am only aware of 1 cranberry supplement that provides 36 mg of bioactive cranberry PACs. It is irresponsible to compare these 2 completely mechanisms of action. Biofilm vs antiadhesion. Antiadhesion is proven in the literature and in practice. The PAC cap the P-Fimbriea (the legs that grab hold of the urinary tract walls) and disable them so that they are washed out of the body. In fact, there is an issued health claim by France’s version of the FDA for this very thing. It is like a drug approval in the U.S.