The Human Effect Matrix (HEM) systematically presents human trial results, so you can see at a glance what effects a given supplement has on a given health outcome.
Existing evidence largely supports an anxiolytic (i.e., anti-anxiety) effect from ashwagandha. The only study that didn’t find such an effect was in people without a specific anxiety disorder (instead, they all had bipolar disorder). To a lesser extent, the evidence also supports a decrease in both cortisol and generalized subclinical stress.
The ancient claims of improvements in vitality seem to be corroborated by reported decreases in fatigue and increases in running speed and lifting power. Small increases in testosterone levels were also noted. Finally, minor improvements in lipids, blood sugar, and inflammatory markers suggest that ashwagandha may help fend off common diseases. For all those health outcomes, however, the research is still preliminary.
Ashwagandha looks promising, and it may have a variety of uses, but we don’t yet know how effective it is in different scenarios or how best to take it. To address those questions, a great many more studies need to be conducted. You can be sure that Examine.com will be watching for them!