Vitamin D is a prohormone of the secosteroid type. It acts as a precursor to what makes a hormone or is a hormone prototype, if you will. Usually exposure to sunlight helps our body (skin in particular) to synthesize Vitamin D. The epidermal layers of Stratum basale and Stratum Spinosum produce maximum amount of a particular type of a pre-vitamin D3. It is fat-soluble in nature. So how is Vitamin D and bone health related?
Vitamin D is metabolised by the liver and the kidneys and is converted to a hormone called Calcitonin. Calcitrol ensures that there is enough calcium in the blood to help form bones, teeth and maintain bone density. When ultra-violet rays shine on our skin, a cholesterol-like substance gets converted to Vitamin D and absorbed into the blood. Vitamin D is required for the metabolisation of calcium.
Several studies are now pointing that mere increase of one’s calcium intake late in life does not offer the same level of protection for bone health you get when vitamin D is added, as well.
A recent study whose results were presented in Boston at the Annual Meeting of the Endocrine Society (June 4-7, 2011) suggested that a bone-density increasing chemical group called bio-phosphates, often recommended to those suffering from osteoporosis and other conditions of bone thinning, in fact showed a remarkable seven times better performance if an individual has at least 33 nanograms (ng) of the nutrient per milliliter of blood (ng/mL). Richard Bockman, M.D., Ph.D., chief of the Endocrine Service at Hospital for Special Surgery, who directed the study said, “If you want to see a particular outcome from this treatment, then maybe 20 to 30 is not appropriate.” (1)
Currently, The National Institutes of Health (NIH) recommends that 20 ng/mL is sufficient for most healthy adults. With the new study, that value does not seem nearly enough for people taking bisphosphonates for accelerated bone loss, said study co-author Richard Bockman.
The best indicator of vitamin D status is thought to be 25(OH)D levels in serum. To ensure adequate 25(OH)D levels, an adult over the age of 50 should consume at least 800 international units (IU) of vitamin D each day, according to the National Osteoporosis Foundation. Taking a daily dietary supplement is a simple way to do so. (2)