Dry skin!

Since the weather changed it started getting colder, I am having some issues with my skin being even more dry than normal.  Mainly where it is bothering me is around my fingernails (lots of hangnails).  I realize that my diet is completely different, but my bloodwork shows I am doing a good job of maintaining my nutrition generally.  Does anyone know if this is caused by a specific problem with your nutrition?  Does anyone have a suggestion of how to deal with it?