All I can tell you is that there are two main supplements I took when I went from having extremely diffuse thinning back in 2007 to very thick hair that I had back in my teenaged years, and that was a concentrated beta sitosterol complex, and evening primrose oil.
By process of elimination I can determine for myself after returning to beta sitosterol, that even talking half a gel capsule made me feel hypo-hormonal to the point where my skin looked dry and aged, and my hair did not improve. Beta sitosterol definitely knocks down your DHT, I know because I've felt it.
However recently I recalled I was using EPO specifically back when my hair really really started growing back, and not to mention the fact that my skin also looked great back then as well, and lo and behold, not only is my hair maintaining, but I am experiencing slow and steady recovery and my skin has gone from looking dry and aged to like I was 30 again, in which I looked quite good and was commonly mistaken for being in my early 20s.
I have taken borage oil and other GLA complexes and I think there is something specific to evening primrose oil that does something beneficial to the hair and skin, I'm so exhausted from the stress of experiencing a second sudden hair loss event that I have wrestled with for a good year and a half, that I'm just happy that it is in fact making me look young and healthy again, and helping my hair maintain and even grow.
Incidentally ever since I got on the estriol and evening primrose oil, I can tolerate taking a LOT more beta sitosterol further improving my hair regrowth (go figure).