Yea, understand all that but seems like it would be difficult to advise players what supplements not to take if you don't know yourself. I get that the players are responsible for what they put in their bodies - and I suppose the option is always there to ask before taking anything that 'could' be a no-no. .... with millions on the line, I certainly would be beyond careful.
Some of these guys are stay ahead of the curve taking performance enhancers that haven't been banned by the league yet guys like James Harrison(Has a FT Dietitian/trainer on staff), JJ Watt(Always doing commercials for weird supplements), and Ray Lewis(Deer Antler spray lol), Peyton Manning(HGH during the off season to extend his career) were/are almost certainly doing this.