But Canada is! And that is what the comment I replied was talking about.

There is pretty much no place in Canada at all that doesn't have a total blackout of availability of Vitamin D from sunlight in the winter.

All the northernmost US states have a period of insufficient sunlight/angle to produce Vitamin D, and basically all of Canada is north of that.

Maybe there's an island that is Canadian territory that is south of say New York or San Francisco that I don't know about of course.