Human (Homo sapiens). Photo in the Public Domain
‘Vitamin D’ (-calciferol) cannot be called a human vitamin because it is an inactive substance made by human cells – regardless of diet – in such quantities that the body can store up to six months’ supply.
The active form is synthesised by the kidney and never acquired from the diet in humans.
Furthermore, a dietary dependence could hardly have evolved.
The best source of vitamin D, namely the liver of game animals, would ancestrally not have been particularly reliable.
Robin and the Honey Badger, 8 January 2017