That cranberries can promote health of the urinary tract and ward off infection is no longer in doubt. But one of the researchers who worked out how is now hedging her bets that this small, red berry holds other bug-beating promise.
In 1998, Amy B. Howell and other scientists at Rutgers University in New Brunswick, N.J., first published work showing that it was substances called proanthocyanidins, or PACs--found in the juice of cranberries--that zap the E. coli bacteria responsible for urinary tract infections. Before then, some researchers had suggested that it was the acidity of the cranberries that did the trick on such infections.
PACs are neither vitamins nor minerals, but one of the many thousands of plant chemical substances found in fruits, vegetables, grains and nuts.
Howell speculates that PACs work by wrapping themselves around E. coli, preventing bacteria from sticking to cells in the urinary tract. The E. coli, she explains, "simply slip out of the tract along with the urine before having a chance to multiply and set up infections."
Having established the bacteria-fighting properties of PACs, scientists wondered where else in the body such a mechanism could be beneficial and soon turned their thoughts to stomach ulcers caused by the H. pylori bacteria latching on to the stomach wall. Early studies by researchers at Tel Aviv University in Israel have found that certain cranberry concentrates can stop adhesion of H. pylori to stomach cells--at least in test tubes.
For PACs to be effective against urinary infections, they must be
transported there after digestion. Howell believes that these plant chemicals could potentially work differently on the bacteria that causes stomach ulcers, going to work immediately after the juice has been drunk and before digestion. Similarly, it is thought that PACs could move directly from the mouth up into the Eustachian tube, which links the mouth to the ear and is often the site of middle ear infections. Like infections of the urinary tract and stomach ulcers, middle ear infections--a common childhood illness--are usually treated with antibiotics.
While researchers attempt to confirm these theories, one thing is for sure: Here is a health regimen you do not have to work hard at.
Amanda Ursell, a dietitian, is a London-based freelance journalist who writes about food and nutrition. Her column appears twice a month.