From an article by Julius Goepp, M.D. in Life Extension, Sept. 2010 :
The cells lining your arteries (endothelial cells) can turn into bone cells as you age. Known as osteoblasts, these cells normally regulate bone formation. The unexpected discovery of osteoblasts in the endothelial lining of individuals with arterial disease was made in 1993.4 It marked a major advance in our understanding of vascular and bone disease. This finding uncovered a previously unknown link between atherosclerosis, which involves calcification of vascular tissue, and osteoporosis, which involves the decalcification of bone tissue.
… Cutting-edge research points to the central role of two key nutrients to ensure optimal calcification of your bones while preventing pathologic calcification of your arteries: vitamins D and K.