There's another aspect to this: Anyone who takes calcium (like my mother, who has osteoporosis, for instance) should also take vitamin K2, and get some more pre-formed vitamin A (retinol) if possible.

Check out "Vitamin K2 and the Calcium Paradox" by Kate Rhéaume-Bleue. For followers of Weston Price, this makes even more sense, since Chris Masterjohn identified K2 as Price's mysterious "activator X".