Having witnessed first hand the unfortunate results of taking multiple "safe" herbal medications which resulted in overdosing on one chemical (common to three of the products) which is safe in small quantities but dangerous in large doses, I'm thinking that some sort of regulation is needed here.
Yes, regulation is certainly needed -- SELF-regulation by consumers. Anyone who is stupid enough to be popping a variety of self-prescribed pills without ascertaining exactly what they contain, deserves to be poisoned. Just like people who go hiking in the woods and start eating whatever mushrooms they find. The only proper role for government here is to facilitate the identification and prosecution of supplement manufacturers whose products' contents differ from the labelled contents.