Vitamin D plays a key role in maintaining strong bones and is the key regulator of serum calcium levels. Calcium is primarily obtained through diet and is absorbed through the intestine and into the blood stream. Vitamin D is important for numerous physiological processes in addition to building bone; For example, Vitamin D regulates calcium levels in the blood stream and determines how much should be stored within the skeleton.
Dr. Geert Carmeliet and colleagues at the University of Leuven in Belgium investigated how Vitamin D laffects the skeleton when serum calcium levels are depleted. Using lab mice that lack the intestinal Vitamin D receptor, the researchers found that the mice still maintained normal calcium levels even when given a low-calcium diet. Further study suggested that Vitamin D stimulated bone cells to produce factors that removed calcium from bone in a process known as bone resorption in order to satisfy normal serum calcium levels. Therefore, although Vitamin D is important for maintaining serum calcium levels, it can also promote bone density loss.
Subsequent studies showed how these findings may explain clinical results where vitamin D supplements failed to prevent fractures in elderly patients, and in some cases, were correlated with increased fracture rates.
Source : http://ping.fm/CigTp
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