Cranberries have a long history as a food as a medicine. It is hard to say when cranberries were first munched by human molars but we do know that Native Americans have used cranberries as treatment for bladder and kidney diseases for many centuries. In the mid-19th century, German researchers found that cranberry had antimicrobial activity and suggested its use in bladder infections. In recent times cranberry has been widely recommended for urinary tract infection (UTI) and now new research is shedding light on exactly how it is working.
First, the researchers found that cranberry powder can inhibit the growth of bacterium called Proteus mirabilis, an organism commonly found to be involved in urinary tract infections. The researchers found that when they increased the concentration of cranberry powder the bacteria produced less of an enzyme known as â€œureaseâ€. This urease is what the bacteria use to spread.
These same researchers have done previous work showing that another bacterium, E. coli, which is involved in bladder infections, is also hamstrung by cranberry. In that research it was shown that cranberry reduced the expression of a gene that E. coli use to produce the flagella filament that allows them to move.
In both cases the cranberry is inhibiting the capacity of the bacteria to â€œswimâ€ and therefore spread and perpetuate the infection. Other research has also shown that cranberry can stop i>E. coli sticking to other bacteria.
Based on its effectiveness against Proteus mirabilis, the researchers suggest that cranberry extract could be used in cleaning implantable devices that can spread UTI, such as catheters. With this possible use, and the fact that 150 million cases of UTI are reported globally each year, cranberry could be a very useful medicine indeed.