As we discussed in the article "IBD and Vitamin D" it is quite common to find patients with Inflammatory Bowel Disease (IBD) to be deficient in vitamin D. The role this plays in the maintenance of bones is a very important discussion.
That having been said, it would be an incomplete story to fail to address the role that calcium plays as well. While vitamin D helps to increase the absorption and mobilization of calcium in the bone, calcium balance is essential in bone mineral density.

