Saw Palmetto
Saw palmetto is a standard medical treatment for BPH utilized by many countries throughout Europe.
The fat soluble extract of saw palmetto berry when used regularly reduces and keeps symptoms in check.
Research suggests that the fat soluble constituents found in saw palmetto berry inhibits an enzyme 5-alpha reductase which in turn converts testosterone to its more active form dyhydrotestosterone (DHT) which in turn binds to prostatic tissue. Interestingly this form of testosterone has also been implicated in male pattern baldness. 23, 24
One European double blind study compared saw palmetto and finasteride, a common pharmaceutical drug used in the treatment BPH. Saw palmetto treated BPH as effectively as the drug with none of the side effects associated with the drug, such as loss of libido. 25, 26
Dose
Many studies have used 320 mg daily of saw palmetto extract standardized to 80 to 95% fatty acids.

23. Schneider HJ, Honold E, Mashur T. Treatment of benign prostatic hyperplasia. Results of a surveillance study in the practices of urological specialists using a combined plant-base preparation. Fortschr Med 1995;113:37–40.
24. Koch E, Biber A. Pharmacological effects of sabal and urtica extracts as a basis for a rational medication of benign prostatic hyperplasia. Urologe 1994;334:90–5
25. Carraro JC, Raynaud JP, Koch G, et al. Comparison of phytotherapy (Permixon®) with finasteride in the treatment of benign prostate hyperplasia: a randomized international study of 1,098 patients. Prostate 1996;29:231–40.
26. Wilt TJ, Ishani A, Stark G, et al. Saw palmetto extracts for treatment of benign prostatic hyperplasia. A systematic review. JAMA 1998;280:1604–9.