What it is
Adaptogen is a pharmacological category, not a single plant. The term was coined by the Soviet toxicologist Nikolai Lazarev in 1947 and formalized by Brekhman and Dardymov in 1969 around three criteria: a substance must raise non-specific resistance to stress, exert a normalizing effect regardless of the direction of the stressor, and be innocuous in ordinary use.
It is a functional definition — what the substance does to the stress-response — rather than a botanical family. Shilajit is described in the review literature as having adaptogenic activity in exactly this sense.
How it works
Adaptogens are understood to act on the body's stress axis — the hypothalamic–pituitary–adrenal (HPA) system — and on molecular stress mediators such as heat-shock proteins and cortisol signalling, nudging an over- or under-active response back toward homeostasis.
Because the category is defined by effect rather than by a shared molecule, the evidence lives at the level of individual adaptogens; the strongest controlled data are for specific botanicals rather than for the class as a whole.
At a glance
What the literature shows
A condensed view. The class is defined pharmacologically; controlled evidence is strongest for specific adaptogens.