This is probably OT, no expertise, but I've read a lot of herbal stuff, (love PFAF website) and one frustration is how often the medical uses of an herb are from 'ancient' and folklore sources.... makes it seems that dozen of plants are 'useful' for dozens of the same ailments...no prioritization of most and least effective. I seem to remember that Germany is an exception to the 'olden days' sources, and had put out many official monographs on individual plants, with accurate info.
Also, being 'supportive' in chronic cases is a little more iffy than immediate effects in acute situations. Plus, there's always the confounding placebo effect...I personally think that our own 'expectations, beliefs and expectations' may be the most powerful healers... btw, (while I'm at it:) I liked 'Suggestible You' by Vance, just overlook the first chapter trashing homeopathy : )
I like this 2004 article, but a lot may have changed in Germany...