The original studies on the inhibition rate of 5AR by the main active ingredients were performed in vivo (on live non human subjects) as well as in vitro (in the test tube) which has proven that DHT production is inhibited by these ingredients up to 98%. Some of the testing such as Saw Palmetto studies also involved human subjects which have shown very good results.

[Note from HairlossTalk.com - a new study was done in 2008 using the actual Revivogen solution on a scientifically approved duplication of the human scalp, and it was proven to be effective in inhibiting the formation of DHT when applied topically, better than Propecia or Dutasteride (Avodart) could. We no longer only need to rely on the individual studies done on the individual ingredients. You can read this new study by finding it on the right sidebar of this page under "Clinical Trials and Related Studies"].