Cranberries have been used widely for several decades for the prevention and treatment of urinary tract infections (UTIs). This is the third update of our review first published in 1998 and updated in 2004 and 2008.
Objectives – To assess the effectiveness of cranberry products in preventing UTIs in susceptible populations.
This updated review includes a total of 24 studies with a total of 4473 participants. Thirteen studies (2380) participants) evaluated cranberry juice/concentrate; nine studies (1032) participants) evaluated cranberry tablets or capsules; one study compared cranberry juice and tablets; and one study cranberry capsules and tablets.
Many studies reported low compliance and high withdrawal/dropout problems which they attributed to palatability/acceptability of the products, primarily the cranberry juice. Most studies of the other cranberry products (tablets and capsules) did not report how much of the ‘active’ ingredient the product contained, and therefore the products may not have had enough potency to be effective.
Prior to the current update, it appeared there was some evidence that cranberry juice may decrease the number of symptomatic UTIs over a 12-month period, particularly for women with recurrent UTIs. The addition of 14 further studies suggests that cranberry juice is less effective than previously indicated. Although some of the small studies demonstrated a small benefit for women with recurrent UTIs, there were no statistically significant differences when the results of a much larger study were included. Given the large number of dropouts/withdrawals from studies and the evidence that the benefit for preventing UTI is small, cranberry juice cannot currently be recommended for the prevention of UTIs. Other preparations (such as powders) need to be quantified using standardized methods to ensure the potency and contain enough of the ‘active’ ingredient, before being evaluated in clinical studies or recommended for use.
Cranberries contain a substance that can prevent bacteria from sticking on the walls of the bladder. This may help prevent bladder and other UTIs. However, D-mannose, a simple sugar not metabolized by the body, attracts the bacteria as it travels through the urinary tract and is a much more effective preventative. It is also better tolerated than cranberry juice.
When treating active UTIs, I will recommend cranberry juice if the pH of the urine is above 7.0 (alkaline). Cranberry juice will lower the pH of the urine which helps fight alkaline-loving bacteria. However, if the pH is much below 7.0 I use A-C Carbromide (arrowroot and carbomide powder) to destroy acid-loving bacteria.
Arginase, an enzyme that catalyzes the conversion of ammonia to urea can also be very effective in the treatment and prevention of recurrent UTIs. I also use it to raise the eGFR (glomerular filtration rate) in patients with compromised kidney function.
The Bottom Line:
If you have a UTI, get a simple urine analysis to determine what product to use to fight the infection. If you suffer from recurrent UTIs consider D-mannose as a preventative.
Source: Cochrane Library, first published Oct. 2012, Cited by 60 articles