CNN's chief medical expert Sanjay Gupta announced Wednesday night that he has reversed his blanket opposition to marijuana use.

Speaking to Piers Morgan, Gupta, who has a documentary on weed airing on Sunday, said he had previously helped to "mislead" the American public about the effects of the drug.

"I have apologized for some of the earlier reporting because I think, you know, we've been terribly and systematically misled in this country for some time," he said. "And I did part of that misleading."

He also wrote an op-ed called "Why I Changed My Mind On Weed." In it, he said that, while he had formerly derided medical marijuana supporters, he had done research that had shown him how beneficial it could be: