President Barack Obama told the New Yorker that if he had a son, he would not allow him to play professional football.
The comments came a year after Obama said he was not sure if he would let his hypothetical son play youth football.
"I would not let my son play pro football," Obama said.
"I'm a big football fan, but I have to tell you, if I had a son, I'd have to think long and hard before I let him play football."
The topic came up in the latest issue of the New Yorker, given the research that connects the physical demands of playing football to concussions, early onset dementia and degenerative brain disease.
Obama also compared NFL players to smokers, in terms of the health risks involved. He said those involved understand those dangers.
"At this point, there's a little bit of caveat emptor," Obama said. "These guys, they know what they're doing. They know what they're buying into. It is no longer a secret. It's sort of the feeling I have about smokers, you know?"