Inside the body Vitamin D's active form is termed calcitrol. The primary role of calcitrol is to increase the flow of calcium into the bloodstream by encouraging absorption of calcium and phosphorous from the food you eat which is stored in the intestines and the reabsorption of calcium in the kidneys. This process allows for the normal mineralization of the bones, which is key to maintaining their density and strength. Osteoporosis develops when bone density is reduced and proteins (both in number and variations) are restricted. Vitamin D plays an essential role in the calcium regulation process in the body. Studies show that people with insufficient Vitamin D levels absorb less than 10% of the available calcium in their systems. Regardless of how much calcium you introduce into your system, if your Vitamin D levels are not properly maintained, the calcium will not be properly absorbed into your system and your bones will not be properly nourished.
However, Vitamin D does more for your bones than simply stimulate the calcium regulation process. Maintaining an adequate storage level of Vitamin D keeps your bones strong. This is particularly important for the elderly, postmenopausal women, and those with movement limitations that cannot regularly exercise. This also benefits bone growth and the remodeling of bones through the cells which are responsible for their formation: osteoblasts and osteoclasts.
