In a double-blind study of over 1,000 men, given either Proscar or saw palmetto for 6 months, the herb was as effective as Proscar -- but without the side effects of Proscar (sexual impotence)! Both treatments shrank the prostate.
Another double-blind study of over 800 men, over one year, found that saw palmetto extract was as effective as the drug tamsulosin (an alpha-blocker used for BPH). Again, saw palmetto was effective without side effects, unlike the drug, plus it cause prostate shrinkage, which the drug did not.
Yet another double-blind trial, of over 500 men over a year's time, found that saw palmetto combined with nettle root was as effective as Proscar? in reducing BPH symptoms.
Finally, another double-blind, placebo-controlled trial of 44 men, over 6 months, showed that a blend of saw palmetto with nettle and pumpkin seed oil caused significant prostate shrinkage, though few changes in BPH symptoms. (The dosage of saw palmetto might have been too low.)