Supplements are pretty much unregulated, and can have some fairly scary ingredients. The regulators generally don't mess with them, until someone (usually multiple someones) has a problem.

Lots of dodgy nutritional supplements out there. Look for NSF Certified Safe for Sport products to be sure of what you're putting in your body.

https://www.nsf.org/knowledge-library/importance-nsf-certifi...

And buy direct from the manufacturer. If you order through a reseller like Amazon then there's always a risk of getting counterfeit products if someone tampered with the supply chain.