One of the leading Magazines "Life Extensions" who specialize in natural products as well as bioidentical hormone therapy says in their Jan/08 article about the Prostate:
"Another enzyme involved in both benign and malignant prostate disease is 5-alpha reductase. The 5-alpha reductase enzyme converts beneficial testosterone into potent metabolite called DHT. DHT provokes a potent stimulatory effect on both benign and malignant prostate cells, The reason Life Extension has long recommended FDA approved drugs like Proscar and Avodart is that they inhibit 5-alpha reductase and thus lower DHT levels. Avodart is more effective than Proscar, but consumers can now purchase a much less expensive generic version of Proscar called Finasteride."
This article mentions how plant lignans reduce DHT....etc..............fyi