Much more vitamin D is needed than was recommended up to now. (Ed note: link fixed)
Drops are a good source for kids.
Adults should get more than we'd thought, too. Again, liquid is the most recommended form.
It's November, and I'm definitely in need of the D. Without it, I don't function as well at all.
If you have older relatives, make sure they are taking plenty, too - it turns out that falls and severe injuries from falls (like broken hips) happen more in the winter not just because it is a) dark, b) slippery, but because vitamin D affects coordination and muscle strength, so low levels mean less coordination, therefore more falls.
I think the feed was messed up, and I think it is fixed now. Hopefully!