You are responsible for ANYTHING & EVERYTHING in your body.
Some thoughts & heuristics regarding Supplements:
1) If it's promises seem too good to be true, don't take it.
2) If it's a 'pre workout', don't take it.
3) If it's made by a company that doesn't sponsor a NRL, AFL or S15 team, don't take it.
4) If it's not made in Australia, don't take it (A study suggests 1/4 of all US supplements are either contaminated or don't have what they claim to have).
5) If you don't need it, don't take it.
6) If it was sold to you by a Gym Junkie, don't take it.
7) If it doesn't have the 'Informed Choice' or the 'Informed Sport' logo on it, don't take it.
8) If you're not sure, don't take it.
Below is a link to the current (January 2016) WADA Prohibited List:
And some information on Prohibited Substances and Methods.
ASADA Help Line: 13 000 ASADA (13 000 27232)