Arian Foster has said that he has seen other players take performance-enhancing substances.
The Houston Texans running back did not reveal the names of those that he claims to have seen using drugs, but said that he did see players using steroids while at college.
The 26-year-old told ESPN Radio: "I've seen and been around guys who juice. I've seen all kinds of things. If you can't get motivated, you can't get motivated.
"Steroids make you stiff. Steroids do things to your body that are [not] conducive to your health. So, if you want me to be strong for the season, yeah, maybe that works and maybe it doesn't. For the long haul, I think it'll hurt your body more than anything.
"I have always been a firm believer of anything that I need can come from the ground. Anything else, I never felt the need. In college, a lot of people took creatine. That was a big thing in college. I never took creatine. I never took muscle shakes or none of that."
Foster is known for his health-conscious lifestyle, following a mainly vegan diet.