Chael Sonnen: Jon Jones tested positive for estrogen blockers
Jon Jones was pulled from UFC 200 after failing a drug test weeks before the event. The interim UFC Light Heavyweight Champion was contrite after his positive test — which was later confirmed with a “B” sample — and said he didn’t even know how to pronounce the substance he tested positive for. But a few MMA insiders have some insight about his failed test.
This is unconfirmed information at this point and has not been sourced by actual reporters nor confirmed by USADA — the drug testing agency employed by the UFC.
Estrogen blockers are considered banned substances because they can be used in conjunction with a steroids cycle. Since an athlete taking steroids would have more testosterone in the body, that would lead to a production of more estrogen (a female hormone that can lead to the production of fat and breasts), which is unwanted for male athletes, hence the estrogen blockers.