This is a remarkable conjecture that the ingestion of menstrual blood is able to access the body itself and provide stimulus. In particular we have the claim of hair returning to its natural color and this explains one other such report from the nineteenth century i came across years ago. It is plausible that experiments took place even then.
Here we are learning of recent work that is surely suggestive. In the end we will want to emulate the reported effects without actually using natural sources and that seems plausible.
This is an unexpected research avenue but also an extremely promising one that conforms to work on stem cells.