The inhibitory effects of methanol extracts of 19 edible and medicinal mushrooms on 5-reductase activity were examined. The extract of
Ganoderma lucidum Fr. Krast (Ganodermataceae) showed the strongest 5-reductase inhibitory activity. The treatment of the fruit body of
Ganoderma lucidum or the extract prepared from it significantly inhibited the testosterone-induced growth of the ventral prostate in castrated
rats. These results showed that Ganoderma lucidum might be a useful ingredient for the treatment of benign prostatic hyperplasia (BPH).