[heavyset_go]

> if it's the process that _creates_ those vitamins that's actually important/healthy.

By definition, vitamins are substances needed by an organism that it can't create itself, and must be obtained in its diet.

[jwilk]

Vitamin D is technically not a vitamin:

https://academic.oup.com/ajcn/article/88/2/491S/4649916#1112...

[dehrmann]

Vitamin D is arguably not a vitamin because we produce it when exposed to sunlight and it's actually a hormone. I guess that makes sunlight the vitamin.

[0_____0]

vit D is an exception here, iirc it's the only 'vitamin' that doesn't fit those criteria