I can't seem to stop myself from writing about pee, and I'm not even a nephrologist. But I deal with pee every day, and many of my younger patients with urinary tract infections will tell me all of the home and herbal remedies they tried before they came to see me. One of the most common alternative treatments is cranberry juice. There are several plausible reasons cranberry juice might work against UTIs.
Some studies have shown that cranberry consumption can acidify urine and raise urinary levels of hippuric acid, a compound that can slow bacterial growth. Subsequent studies have found that it is nearly impossible to consume enough cranberry products to significantly change the pH of the urine or to raise concentrations of urine hippuric acid.
Other studies have found that some of the chemicals in cranberry juice can prevent E. coli from adhering to the urinary tract lining. Since E. coli are the cause of a high percentage of UTIs, this could be significant. Unfortunately, studies have failed to show significant clinical benefit in several types of UTIs, especially when compared to usual antibiotic therapy.
Adding to our database is a study in the latest issue of Clinical Infectious Diseases. This study looked at preventing recurrent UTIs in young women, a group at significant risk for recurrence.
The results were unimpressive. During the six months of follow up, the cranberry juice group did not have significantly fewer recurrent UTIs than the placebo group. One caveat to this conclusion is the observation in previous studies that the effect of cranberry is dose-dependent. In the study, women were given eight ounces of cranberry juice cocktail daily. It could be argued that this is too little to have an effect. But to drink, say, 24 oz of low-cal cranberry juice cocktail daily hardly seems like a reasonable trade off. That's a lot of juice.
For now, I'm not recommending cranberry juice to my patients wishing to prevent UTIs.
Barbosa-Cesnik, C., Brown, M., Buxton, M., Zhang, L., DeBusscher, J., & Foxman, B. (2011). Cranberry Juice Fails to Prevent Recurrent Urinary Tract Infection: Results From a Randomized Placebo-Controlled Trial Clinical Infectious Diseases, 52 (1), 23-30 DOI: 10.1093/cid/ciq073
Raz, R., Chazan, B., & Dan, M. (2004). Cranberry Juice and Urinary Tract Infection Clinical Infectious Diseases, 38 (10), 1413-1419 DOI: 10.1086/386328