Thirteen vitamins are considered essential to the human body. On that list is vitamin D, also referred to as the sunshine vitamin. Despite its classification, vitamin D is not a true vitamin: The body can produce the amounts you need, as opposed to getting them only through dietary sources. In fact, if you receive adequate exposure to sunlight, your vitamin D levels may not need supplementation.
Where Does it Come From?
The vitamin D group of nutrients are fat-soluble and become available to your body in a variety of ways. For instance, your body creates vitamin D3, or cholecalciferol, after your skin encounters the ultraviolet rays in sunlight. Whatever level of vitamin D your body does not create from sun exposure, it must receive from your daily diet in order to stay healthy. Dietary vitamin D is available in foods such as eggs, fish oils as well as milk and other foods fortified with the nutrient.
How Does Your Body Activate it?
Vitamin D does not go to work on its own; your body has to activate it. Colorado State University explains that after your body creates vitamin D, your liver and kidneys transform it into an active hormone that your body can use. This active hormone is known as 1,25-dihydroxycholecalciferol. Once activated, the hormone binds to carrier proteins in your bloodstream and is transported to the mucosal cells of the intestines to aid in the absorption of calcium. It also travels to all of the cells in your body, where it plays a role in DNA transcription and immune system function.
What Does it Do?
Without vitamin D, your intestines do not absorb calcium efficiently. Your bones rely on calcium and vitamin D to make them stronger, and if either are absent for an extended period of time, your bones can become weak and brittle. Like your bones, your teeth also need vitamin D and calcium. Deprived of either, your teeth become soft and susceptible to decay. Your immune system also needs vitamin D to remain strong. If your body doesn't have enough vitamin D, you may become sick and vulnerable to disease.
Vitamin D Supplements
If you are under 70 years of age, the Recommended Dietary Allowance for vitamin D is 600 IU, or 15 mcg, daily. An adequate intake for babies from 0 to 12 months old is 400 IU, or 10 mcg, and people over age 70 need 800 IU, or 20 mcg. If your doctor suspects that you are not getting enough vitamin D, he may recommend a supplement. Over-the-counter supplements are synthetically manufactured versions that mimic the true vitamins and sell in capsule, tablet and liquid forms. Be aware, however, that taking too much vitamin D in supplement form can lead to toxicity, so discuss dosages with your doctor before beginning supplementation.
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