Saw Palmetto (Serenoa Repens) is very well known as a natural remedy for benign prostate hyperplasia. Saw palmetto sterols have been shown to inhibit 5alpha-reductase activity, the enzyme responsible for conversion of testosterone to dihydrotestosterone and to inhibit binding of dihydrotestosterone to the cytosolic androgen receptor.
More simply stated, Saw Palmetto works to combat the detrimental effect of testosterone on male hair loss. Saw Palmetto has been found to curb the conversion of testosterone into DHT. This can be especially helpful for stubborn acne cases where DHT is a factor.
On a slightly different note, this active has been shown to be effective in some cases in minimizing hirsutism, the excessive growth of thick dark hair in locations where hair growth in women usually is minimal or absent.