evlovingstuff - I think you'll like this article about K & D interaction:

http://www.lef.org/magazine/mag2010/sep2010_Brittle-Bones-Ha...

Here is the summary: "The remarkable discovery that blood vessel cells can transform into bone-forming cells confirmed the little-known link between atherosclerosis and osteoporosis. At the core of this connection is insufficient D and K intake. These vital nutrients operate in synergy to optimize bone mineralization and prevent calcium deposits in vascular tissue. Low vitamin D is linked with arterial disease and bone loss, while vitamin K stimulates bone formation and modifies specific proteins (Gla) that help protect against arterial calcification.

Vitamin D taken in higher doses (5,000-10,000 IU/day) has become popular over the last two years based on findings showing that this potency is required to achieve optimal blood levels (over 50 ng/mL of 25-hydroxyvitamin D). Relatively few supplement takers, however, understand the critical need for aging humans to also take a daily vitamin K supplement. Fortunately, Life Extension members were informed in 1999 about the critical need of including vitamin K in their supplement regimen."