It always somewhat surprises me how some interventions never seem to die. One therapy that refuses to be put to rest, or even to be clarified, is the use of cranberry juice for urinary tract infections (UTIs). PubMed references go back to 1962, and there are over 100 references. Firm conclusions are still lacking.
There is a reasonable, but incomplete, basic science behind the use of the cranberry juice for UTIs. E. coli , the most common cause of UTIs, causes infection in the bladder by binding to the uroepithelial cells. To do this, they make fimbriae, proteinaceous fibers on the bacterial cell wall. Fimbriae are adhesins that attach to specific sugar based receptors on uroepithelial cells. Think Velcro. Being able to stick to cells is an important virulence factor for bacteria, but not a critical one — it is not the sine qua non of bladder infections.
Are all E. coli causing UTIs fimbriated? No. It is the minority of E. coli that cause UTI that have fimbria, and the presence of fimbriae may be more important for the development of pyelonephritis (kidney infection) than cystitis (bladder infection). Read more »
*This blog post was originally published at Science-Based Medicine*