Researchers from Worcester Polytechnic Institute, in Massachusetts went into the lab to seek the answer.

First, the details.

• Atomic force microscopy was used to study the adhesion forces between Escherichia coli and a model surface (silicon nitride).
• The objective was to determine the effect of cranberry products to change the ability of bacterial to adhere to the surface.
• Bacteria were grown in tryptic soy broth supplemented with either light cranberry juice cocktail or cranberry proanthocyanidins (PACs; have antioxidant properties).

And, the results.

• Longer exposure of the bacteria to either the cranberry juice or the PACs resulted in a greater decrease in bacterial attachment to the surface.

The bottom line?
Assuming that silicon nitride is appropriate for this research, the results indicate that chemicals present in cranberries — and not the acidity of cranberry juice, as previously thought — prevent infection-causing bacteria from attaching to the cells that line the urinary tract.

Studies in patients supporting the use of cranberries are summarized here, here, here, and here.

3/12/09 20:56 JR