Astragalus Membranaceus has just been added to the inventory, and it is a weird one. Among plants, it is unique; among supplements, the body of evidence is also unique.
It has a ton of human studies on it already
Aside from inhibiting CYP3A4 (harmless itself, but could adversely interact with pharmaceuticals) it appears to have no side effects
It has some amazing studies behind it, such as the case study citing Astrgalus (15g whole plant daily) for curing a kidney disorder
It seems to be a reliable and potent kidney health supplement, which are not too common to come across
Some topics, such as muscle protein synthesis and testosterone, are unexplored. Neurology is also not studied too much, aside from being able to protect the brain from damages
A very large amount of human studies are via injections, and thus due to the poor bioavailability of Astragaloside IV it is not sure if the potency seen can extend to oral consumption of Astragalus
The reason for the poor bioavailability of Astragalus doesn't seem to be one that can be aided by coingestion of ingredients (like how curcumin has it's bioavailability enhanced by black pepper extract) so we may be stuck with poor absorption rates
A lot of studies use the whole extract, and do not specify which component (saponins, flavonoids, polysaccharide, etc.) is the active fragment; meaning it would be prudent to use the whole plant rather than isolated components
For the most part, this herb seems to be very nice for circulatory and kidney health as well as a general 'protective tonic' to use words form Chinese Medicine. If we had more studies done on other body organs, it is possible that Astragalus could be a 'panacea' (using that term loosely here) but it is too preliminary to come to a conclusion. It is quite promising though.
It is a bit unfortunate that the best benefits are seen with such a high dose of root extract (15-30g) as most supplements are geared towards 500mg to 1g. The lower doses give benefit, but this is one of the few supplements that may follow a 'more is better' relationship until your intestines tell you to stop.
Over the past few months, Astragalus Membranceus appears to be one of the more promising additions to the inventory from a supplemental point of view. I look forward to new and exciting studies on this herb, and wish for great things from it.