Interesting you mentioned K-2. I have a friend with osteoporosis who got a 10% increase in bone density in less than one year taking k-2 along with the calcium supplement. Anecdotal, sure.
VITAMIN K2 AND THE CALCIUM PARADOX
There is also evidence that this deficiency of K2 contributes to the plaque in arteries. K2 helps to get the calcium into the bones. Calcium, Vitamins D3,K2, and A all work together for strong bones.