Documentary What the Health has been been a smash hit - turning people vegan in their droves.
With great success - comes great scrutiny, and the film has certainly been challenged along the way.
One of the film's loudest critics is Joe Rogan.
What does Dr. Milton Mills have to say about that?
"It's very easy to make an unfounded claim, but if he doesn't back it up with specifics, what would I say to Joe Rogan?
"Joe Rogan, you need more fiber in your diet. Because you're full of it."