Since my main certification is though ACE – and I’m not a dietitian or a doctor – I abide by this position statement found on their website:
Let me know if you still have any questions and/or concerns. I’d be happy to elaborate more on the subject.
The personal trainer would need to refer to the code of ethics of the organization that they are certified by. Each certification body has their own code of ethics.
As fitness professionals we have a scope of practice, the scope of practice delineates what is within and outside of our professionals.
It is not within the scope of practice of fitness professionals to recommend supplements.
Best to you.