this herb appears to have had far more scrutiny than most and to have come out looking better

I disagree. (With all due respect-- this is an area that I've worked professionally in, and rhodiola seems to me to be rather typical for a well-known folk herbal.) I would say that it has a long history of ethnopharmacological use in traditional herbal practice. But so do many Ayurvedics and TCM's that have recently uncovered toxicity or contraindications, too. It's probably okay since there doesn't seem to be any ACUTE toxicity noted. However, that says nothing about chronic toxicity or clearance times.

Mechanism is unknown. It's assumed, but unconfirmed. (And honestly-- in some cases, actively contradictory from one study to the next.)

That means that any suggestions about what the active component actually is are conjecture at this point. You can't really "standardize" what you can't identify.

There are some disconcerting reports in the older literature that indicate that it might be pretty dirty stuff from a pharmacology standpoint. Antiarrhythmic affect may well indicate cardioactive principles such as beta-blockers or MAO/ACE inhibitors.

http://www.drugs.com/npp/rhodiola.html

http://altmedrev.com/publications/7/5/421.pdf

Even the fairly generous (IMO) latter review uses terms like "purported," "assumed" and "putative" when describing activity and mechanism.

This is more concrete-- but as a parent, this would scare me, honestly, more than it would reassure me:

http://www.ncbi.nlm.nih.gov/pubmed/23430930

A lack of toxicity data doesn't mean that it is safe-- only that nobody has examined it and published those findings.


Other reviews that I think are well worth looking into:

http://www.ncbi.nlm.nih.gov/pubmed/19468971

http://www.ncbi.nlm.nih.gov/pubmed/22643043

Schrödinger's cat walks into a bar. And doesn't.