Effects of pollen extract preparation Prostat/Poltit on lower urinary tract symptoms in patients with chronic nonbacterial prostatitis/chronic pelvic pain syndrome: A randomized, double-blind, placebo-controlled study 

A double blind, placebo-controlled trial from 2006, followed 60 patients with chronic non-bacterial prostatitis/chronic pelvic pain syndrome. They were randomized to treatment with Prostat/Poltit (222 mg flower pollen) or placebo daily for six months. Of the patients who took the pollen extract, 73% had clinical improvements with 20% of participants having complete resolution of symptoms. By comparison, 35% of participants in the placebo group had clinical improvements and none with complete resolution of symptoms. 

References:

Elist J. (2006). Effects of pollen extract preparation Prostat/Poltit on lower urinary tract symptoms in patients with chronic nonbacterial prostatitis/chronic pelvic pain syndrome: a randomized, double-blind, placebo-controlled study. Urology. 67(1): 60-3