Recent research has cast new light on how cranberry proanthocyanidins (PACs) actively disable certain bacteria such as E. coli, preventing them from adhering to cells in the body where they could potentially cause infection. With many bacteria becoming increasingly resistant to commonly prescribed antibiotics, the anti-adhesion properties of the cranberry are emerging as a potentially significant step towards finding a viable means to reduce our dependence on antibiotics by reducing the risk of initial infections.

Long known for their ability to reduce the risk of infection in the urinary tract, cranberry PACs have now been shown to work at molecular level in three ways to prevent bacteria adhering to cells in the body, a necessary first step in all infections. The laboratory research, conducted at Worcester Polytechnic Institute (WPI) , revealed that cranberry PACs create a natural barrier that stops certain bacteria from binding to cells in the body. Cranberry changed the shape of the bacteria from rods to spheres, also altering their cell membrane, and making it difficult for bacteria to make contact with cells – or from latching onto them should they get close enough. Certain E. coli bacteria exposed to cranberry juice seem to stop secreting indole, the molecule responsible for the inter-bacterial communication that triggers bacterial attack.

Kristen Girard, principal scientist in food ingredients at Ocean Spray ITG, said: “We have always believed that the might of the cranberry is still largely untapped.

“These findings contribute to the considerable body of scientific evidence for what we have long known – that the unique properties of cranberry actively help minimise the risk of urinary tract infections. We welcome the results of this study and look forward to the next phase of research.”

The anti-adhesion activity of cranberry PACs is primarily due to its unique A-type structure. While most foods only contain the more common B-type PACs, it is believed that cranberry’s unusual A-type PACs are responsible for this anti-adhesion mechanism. Since cranberry PACs also function as antioxidants, they provide a dual anti-adhesion and antioxidant health benefit. With more PACs and antioxidants per gram than most fruit, cranberries ward off certain bacteria and bolster the body’s defenses against free radical damage that can contribute to many chronic diseases including heart disease.