Green tea increases testosterone and dht; black tea increases testosterone but decreases dht. (Search the net, there was a japanese study.) Green tea makes my skin worse as well, whereas the black one has no influence. But if you're looking for a way to systematically lower dht keep in mind that it fulfills necessary functions in the body - so that systematic inhibition can cause severe problems concerning skin and brain issues among others. (E.g. search the net for finasterid (a 5ar-inhibitor) and brain fog...)