It is widely used for the treatment of enlarged prostate glands in men. Prostate glands become enlarged partly because of a male hormone called dihydrotestosterone, or DHT.
Women with PCOS tend to have higher levels of DHT than other women. Therefore, if saw palmetto works for men, it may work for women.
Excessive levels of DHT in women has been linked to acne, hirsutism (hair growth in the "wrong" places), and female pattern hair loss.
Female hair loss is one of the most troubling and difficult aspects of polycystic ovary syndrome. It is caused in part by DHT, which causes the hair follicle to shrink and thus causes the hair shaft to be discarded. The result is thinning hair on the scalp.
The Journal of Alternative Complementary Medicine published a study showing that saw palmetto may slow down this hair loss process. This was a small study of ten men. Six of the ten men taking saw palmetto had reductions in their hair loss.
The type of hair loss that men have is similar to the most common type of hair loss that PCOS women have. Therefore, if saw palmetto works for men, it should also be helpful for women who have PCOS and hair thinning.
Because of its inhibitory effect on the male hormone DHT, saw palmetto should be useful for acne and hirsutism in addition to hair thinning.