Yeah, very poor wording on my part as I was addressing the false claim in GP that only sunlight-based synthesis would provide vit-D. Diet is an alternate source. More in my other follow-up response.
I said that they couldn't have another way to synthesise vitamin D than sunlight, it can only be synthesised by sunlight. So for the Inuit, vitamin D mostly comes from diet.
The claim I was responding to was "they [unlike other humans] don't need sun to produce vitamin D". They do, they just don't rely much on this source because it doesn't work in their environment.
