Cranberry has a long history of relieving symptoms of urinary tract infections, and researchers believe they know why: the fruit contains phytonutrients called proanthocyanidins (PACs), and more specifically A-type PACs, which are not found in other berries. A-type PACs help prevent bacteria from attaching themselves to the walls of the urinary tract, which in turn helps prevent the development of urinary tract infections.
This quality makes cranberry helpful in managing symptoms of prostatitis, which can include urinary urgency, urinary flow problems, and urinary frequency.
In a study published in the British Journal of Nutrition, men with chronic nonbacterial prostatitis and lower urinary tract symptoms were given either 1,500 mg dried powdered cranberries daily for six months or no cranberries. Men who received the cranberries showed significant improvement in urinary symptoms and had a lower total PSA than did those in the non-cranberry group.
A typical dose to support urinary tract health is 500 mg daily, but consult your healthcare provider, because cranberry contains high levels of oxalate, chemicals that can increase the risk of kidney stones. (Sengupta 2011)
Sengupta K et al. A randomized, double-blind, controlled, dose dependent clinical trial to evaluate the efficacy of a proanthocyanidin standardized whole cranberry (Vaccinium macrocarpon) powder on infections of the urinary tract. Current Bioactive Compounds 2011 Mar; 7(1): 39-46
Vidlar A et al. The effectiveness of dried cranberries (Vaccinium macroaarpon) in men with lower urinary tract symptoms. British Journal of Nutrition 2010 Oct; 104(8): 1181-89