Do cranberries help prevent urinary tract infections?

Cranberries are widely used in the treatment and prevention of urinary tract infections (UTIs) and for those at risk of such infections. With the growing resistance to antibiotics, cranberries can be viewed as a useful non-pharmaceutical remedy (Lavender, 2000). The initial studies that looked at the effects of cranberries on urine showed that the excretion of hippuric acid from the berries helped the urine to remain acidic, which could explain why they could be used to treat and prevent infection (Harkin, 2000). Recent studies argue that cranberries prevent Escherichia coli (E. coli) from adhering to uroepithelial cells in the bladder (Howell and Foxman, 2002). Cranberries contain a group of compounds, called proanthocyanidins, which are condensed tannins (Gray, 2002; Lowe and Fagelman, 2001; Kuzminski, 1996). These are thought to be the key factors in inhibiting E. coli adherence.