"I mean, one of them says, you know, take a pill and you'll be thin — from your lips to God's ear, wouldn't we all love that?" she said. "Not true, not medically true, not scientifically true, and Dr. Oz knows it, and he does it all the time."
"Then we've got Donald Trump promising things that are totally not true, lying every time, almost, he opens his mouth," McCaskill continued. "So I think it's a marriage made in heaven, Dr. Oz and Donald Trump."
McCaskill has criticized what she views as Oz's dubious medical advice before, including leading a committee hearing in 2014 during which Oz tangled with lawmakers from both parties over his claims certain substances cause "miracle" weight loss.
At one point during the hearing, Oz told lawmakers that his "job is to be a cheerleader for the audience when they don’t think they have hope."
Trump appeared for a taping of "The Dr. Oz Show" on Wednesday in what represented another celebrity-dominated day in the presidential race.
Trump handed the television personality a one-page summary of his recent physical and at one point asked the audience with a shrug if he should release his medical records.