Pierre,

It is my understanding that sunflower seeds contain a lot of vitamin D.
Some mushrooms contain vitamin D.  Bee pollen contains vitamin D.  And of
course, if you are willing to eat raw seafood, that also contains vitamin
D.

Up here in Michigan I have the same problem you do.  I try to get a lot
of sun in the warm months.  I think I read somewhere that the body can
store vitamin D for up to 6 months.
					Bob