In recent years, vitamin D3 has made headlines for being something of a "wonder" nutrient for being linked to the prevention of many diseases, such as heart disease and certain cancers, as well as autoimmune disorders like multiple sclerosis. However, there's still lots to learn about this ubiquitous "vitamin." It's not just for bone health anymore.
Different Chemical Forms
As with most vitamins, vitamin D exists in nature as several different forms. The three main forms of vitamin D are cholecalciferol, calcidiol, and calcitriol. Vitamin D3 in chemical terms is called cholecalciferol. As the name suggests, vitamin D3 production is related to calcium and cholesterol and it requires fat or lipid for absorption and utilization. In other words, it is fat soluble. In the body, cholecalciferol, or vitamin D3, is made into calcidiol, which is a precursor to the hormone calcitriol. Calcitriol is a very potent steroid hormone that has numerous health benefits. It is sometimes considered the active form of vitamin D even though cholecalciferol is the most potent dietary form.
Functions of D3
Vitamin D3 is best known for its role in preventing rickets, a childhood condition of brittle, deformed bones. In adults, it is also critical for maintaining bone mineral density and preventing the adult form of rickets, osteomalacia. Beyond bone health, this vitamin -- which some experts argue is not a vitamin at all, but a hormone -- also plays significant roles in cancer prevention, immune function, mood and nervous disorders.
Food and Supplement Sources
Food content of vitamin D3 is measured in international units or IU. Adding to argument that perhaps it's not a vitamin, very few foods are a good source of vitamin D3. By definition, a vitamin is present in natural foodstuffs, not added through fortification as is the case with vitamin D in milk, cereal and margarine. Small amounts of naturally occurring D3 is found in oily fish and cod liver oil, egg yolks, beef liver and cheese. However, these amounts are generally less than 40 percent of the daily requirement of 1,000 IU recommended by the Canadian Cancer Society. To obtain this amount, most people would have to take a supplement of vitamin D3. These are available in drop form or tablets.
Vitamin D3 Toxicity
Vitamin D experts such as Dr. Zoltan Rona have advocated for high doses of vitamin D3, as high as 10,000 IU per day, claiming that this level of supplement does not harm the kidneys or interfere with calcium metabolism. This is the subject of ongoing controversy in the medical and alternative health fields.
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