Also known as 1,4,6-androstatriene-3,17-dione. ATD is an aromatase inhibitor included in various bodybuilding supplements designed to reduce estrogen and boost natural testosterone.
ATD has been used extensively in zoological investigations (“Influence of gonadal hormones on the development of parental behavior in adult virgin prairie voles” is a representative title)—but human data is lacking. The only relevant research on A”TD is two small studies on Novedex XT, a supplement that contains two other ingredients as well.
Nonetheless, it apparently works and is not known to be toxic. Despite the limited amount of human research, a patent application for ATD has been filed for—among other things—the improvement of male fertility and athletic performance.