PSO is rich in beneficial nutrients, such as essential fatty acids, β-carotenes, lutein, γ- and β-tocopherols, and phytosterols [25]. It has been reported in several animal studies that PSO inhibits testosterone-induced hyperplasia of the prostate and suggested that PSO may be beneficial for the management of BPH [10, 24]. Another study confirmed that the intake of PSO at 320 mg/day over 12 months is clinically safe and effective as a complementary treatment for BPH [11]. Although the action mechanism is still unclear, previous animal studies have suggested that PSO may inhibit 5α-reductase, which produces DHT from testosterone [11, 12, 26].
Our study has some limitations, which include a lack of histological confirmation of the action mechanism of PSO. In addition, DHT and prostate specific antigen (PSA) levels were not measured for identification of mechanism of PSO; therefore we could not explain the exact action of PSO on AGA patients.