With respect I think this is misleading, because there is at least one fine example of a European living for a full year with the Inuit eating the same diet as them and surviving and thriving.
I suspect that the Inuit also have/had some access to Vitamin C through berries traded from further South. As far as I know not all Inuit lived their lives 100% ice bound.
The sometimes reliable Wikipedia says:
"
Vitamins and
minerals which are typically derived from plant sources are nonetheless present in most Inuit diets. Vitamins
A and
D are present in the oils and livers of cold-water fishes and mammals.
Vitamin C is obtained through sources such as caribou liver,
kelp,
whale skin, and seal brain; because these foods are typically eaten raw or frozen, the vitamin C they contain, which would be destroyed by cooking, is instead preserved."