Of course some believe that Vitamin D is a substance only required to prevent rickets, while others have assigned it all kinds of different roles so they would be unlikely to accept absence of rickets as a standard.
> Of course some believe that Vitamin D is a substance only required to prevent rickets, while others have assigned it all kinds of different roles
The phrasing there is a little weird. Conceptually you wouldn't expect Vitamin D to have the function "preventing rickets", in the same way that the function of Vitamin C is not "preventing scurvy". Vitamin C does several things, and the different failures of those different things manifest as different symptoms of scurvy. Scurvy is what happens when you don't have enough Vitamin C, as rickets is what happens when you don't have enough Vitamin D.
