Medscape takes a negative view for prevention and treatment of infection.
Dr. Lie from the University of California at Irvine tells us the following.
- Evidence for cranberry juice to prevent bacteruria and pyuria (signs of infection) in the elderly is equivocal, based on a 2008 Cochrane review.
 - No evidence for treating urinary tract infections (UTIs), based on a 1998 Cochrane review.
 - Cranberry juice cocktail in children with neuropathic bladders shows no benefit.
 
And then, there are the side effects.
- Case reports of warfarin drug interactions and increased bleeding risk.
 - Increased risk for calcium oxalate renal stones and hypersensitivity.
 - The caloric content of cranberry juice if consumed daily in large amounts.
 - Gastrointestinal distress, including diarrhea.
 - Risks in patients with a history of kidney stones, although it has been observed that cranberry products may have a role in the prevention of kidney stones.
 
The bottom line?
The distinction between treatment and prevention is important.
I was attracted to the Cochrane Review in 2008, which rather than “equivocal,” concluded “There is some evidence that cranberry juice may decrease the number of symptomatic UTIs over a 12 month period, particularly for women with recurrent UTIs.”
A summary of that Cochrane review is here.
Importantly, there is no evidence for cranberry as a substitute for antibiotics to treat UTI, as Dr. Lee points out.
All of this is probably mute, since I defy anyone to drink the recommended amount of cranberry juice day after day — 90 to 480 mL of cranberry cocktail twice daily or 15 to 30 mL of unsweetened 100% cranberry juice daily.
6/5/08 18:29 JR