I'm wondering how aware people would have been, hundreds of years ago, of pernicious anaemia and its symptoms and that it could have caused death?
Not sure when they discovered Vit.B12 keeps it in check.
Also, whereas (I believe) its prevalence increases with age, in the dim dark ages people may have put down the general decline and symptoms as just being part of old age?
(My dad developed it at around 80, and I discovered at around 65 that I have it too.)
Dawn M