Vitamin D is a unique compound, in that the body can make it with the help of sunlight. Like Vitamin A, Vitamin D is also important in bone formation. This is because, while Vitamin A works to help in remodeling the bones, Vitamin D on the other hand, helps to mineralize (harden) the bones. In a team effort or collaborative approach, Vitamin D works with Vitamin A, Vitamin C, Calcium, Phosphorous, Magnesium, Flouride, and certain hormones in bone formation. Vitamin D also interacts with other nutrients, such as Pantothenic acid which is essential in its synthesis. Vitamin D is a fat-soluble vitamin in that it requires at least 10% of dietary fat for the body to adequately absorb it.
Vitamin D's specific task is to make sure that Calcium and Phosphorus (the two minerals responsible in completing the process of bone formation), are available in the blood. Along with other hormones, Vitamin D tightly controls the Calcium concentration in the blood and body fluids. As soon as Calcium concentration in the blood reaches its highest peak, Vitamin D directs Calcium to be deposited into the bones. In contrast, when Calcium levels get too low, Vitamin D will work to help correct the problem by enhancing Calcium absorption in the intestine, releasing Calcium from the bone, and reducing Calcium excretion through the kidneys, to normalize blood Calcium levels.
Food does not directly affect Calcium concentration in the blood. It is the regulatory control system that directly affects blood Calcium levels. For example, when your blood Calcium level is too low, it results in a condition called "Calcium Tetany". This condition is manifested by uncontrolled muscle tissue contraction due to the changes in the nerve cell stimulation. The reported possible cause of this is due to a lack of Vitamin D, or problems in the regulatory system in which Vitamin D is a part of. It is however, noteworthy that prolonged inadequate intake of Calcium can lead to a decreased amount of bone Calcium reserves. Because the blood thrives to maintain its Calcium levels, dietary intake of Calcium and Vitamin D is very important to keep the bones from giving up their reserves, thus preventing the bones from becoming fragile and brittle.
Vitamin D was originally thought to be a hormone rather than a vitamin. This is because Vitamin D works just like a hormone. Hormones are made by one body organ to influence another. Vitamin D precursor is made by the liver which is then released into the blood and circulated to the skin. Once this compound in the skin is exposed to the ultraviolet rays of the sun, it goes back into the blood stream. In the blood stream, it goes through several conversion steps in which the liver and kidneys work simultaneously to produce a final product - active Vitamin D. Active Vitamin D then works to promote the making of specific proteins and helping protein work on their specific tasks. This is why, if a person has a kidney or liver problem, bones are also affected and ultimately deteriorate.
The Essential Guide to Vitamins and Minerals by Elizabeth Somer
A single-volume, heavily researched reference covers such areas as the role of each vitamin and mineral, deficiency symptoms, vitamin fallacies, the role of vitamins in disease, antioxidants, and overall health improvement.
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Functions
- Formation and maintenance of normal bones and teeth
- Maintains normal nerves and muscle - (muscle contraction, such as heartbeat)
- Normal hearing - maintains healthy small bones of the inner ear
- Normal Insulin Secretion - Vitamin D is shown to help the normal production and secretion of insulin from the Pancreas, thus helping regulate blood sugar.
- Prevent Cancer - Vitamin D may help prevent cancer cell growth, such as Colon cancer and Non-Hodgkin's Lymphoma.
- Boosts Immune system - Vitamin D helps regulate immune function by defending the body from infectious diseases.
Deficiencies
Vitamin D deficiency decreases the absorption of Calcium, which can lead to low levels of Calcium in the blood, thus resulting in brittled bones. The table below lists other Vitamin D deficiencies.