There are five different types of Vitamin D (D1, D2, D3, D4 & D5), but D2 and D3 are the only types that our bodies can use. When something just says "vitamin D" it is generally referring to D2 or D3 (or a combination of the two). Vitamin D is a pro-hormone, which is the precursor to a hormone. In its raw form (sun exposure, foods, supplements), Vitamin D is inert and has to go through a series of complex biochemical reactions before your body can use it. These reactions produce calcitriol, which is the form of Vitamin D that is used by your body (D2 and D3). Vitamin D is one of the only vitamins that your body can produce by itself. What is the catalyst that gets your D production going? Good old-fashioned sunshine! It's the ultraviolet-B radiation (UVB) that enables vitamin D production to occur in the skin. Vitamin D is produced in equal amounts in both people with fairly pigmented and darkly pigmented skin after exposure to UVB radiation (sunlight) . Sunlight is important for Vitamin D production, but the strength of sunlight and the intensity of UVB exposure can be affected by season, distance from the equator, and even personal habits. If you have a job that keeps you indoors during daylight hours, or you work nights, you don't produce as much Vitamin D as someone who is outside for at least ten to fifteen minutes each day.
Vitamin D can be supplemented by eating the right foods. See my previous blog post about foods containing Vitamin D.
Benefits of Vitamin D
Vitamin D supports bone development by enabling calcium uptake by your body. It is also important for healthy immune system function and may help lower your risk of contracting colds . Vitamin D also helps confer innate immunity which may protect your body from the influenza virus . Vitamin D has had a positive effect on many different diseases, including multiple sclerosis , arthritis  and even cancer . Children with higher vitamin D levels are less likely to suffer from asthma  and allergies than those who are vitamin D deficient. Mental agility might be maintained by adequate levels of the vitamin, especially in the elderly . Because Vitamin D promotes calcium absorption, it is important for bone mineralization (hardening), which keeps your bones strong and supple. A sufficient amount of Vitamin D helps prevent joint discomfort.
There is also evidence suggesting that Vitamin D may play an important role in weight loss , both in adults and in children. Some researchers are exploring whether vitamin D may act as a natural protector from low levels of radiation , such as the background radiation we receive from sunlight and other sources.
Symptoms and Causes of Vitamin D Deficiency
There are no clearly defined causes of vitamin D deficiency. However, the obvious culprits are not eating right and a lack of activity in general, but especially outdoor activity. Adults and children who have poor diets are especially at risk. Risk factors for being vitamin D deficient include race, gender, and lifestyle, including time spent watching TV, playing video games or sitting in front of the computer.
People at high risk of having Vitamin D Deficiency Syndrome (VDDS) are often those who suffer from other disorders, such as autoimmune diseases, heart disease, osteoporosis, chronic pain and fatigue, and certain cancers. Symptoms of some of these disorders can be lessened by taking a Vitamin D supplement or eating more foods with vitamin d. Other diseases and disorders, such as rickets, rheumatism, and osteoporosis (bone disease) can be exacerbated by a lack of vitamin D in the body . Hypocalcemic tetany, a condition in which the body is low in calcium due to vitamin D deficiency, causes overactive neurological reflexes, spasms of the extremities (hands and feet) and larynx, and muscle cramps. Calcitriol, the form of vitamin D your body uses, plays a key role in the maintenance of many organ systems.
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- Sue McGreevey. Risk Of Colds And Flu May Be Increased By Vitamin D Deficiency. Medical News Today. MediLexicon, Intl., 2009 February 24.
- Cannell JJ, Zasloff M, Garland CF, Scragg R, Giovannucci E. On the epidemiology of influenza. Virol J. 2008 Feb 25;5:29. doi: 10.1186/1743-422X-5-29. Review.
- Kathleen Wets. Link Between Vitamin D And Reduction In Multiple Sclerosis Risk. Medical News Today. MediLexicon, Intl., 2009 May 28.
- n.p. High vitamin D intake linked to reduced risk of rheumatoid arthritis. Medical News Today. MediLexicon, Intl., 2004 January 12.
- Cancer Treatment Centers of America. Study Suggests Vitamin D Screening And Appropriate Supplementation Indicated For All Cancer Patients. Medical News Today. MediLexicon, Intl., 2009 June 16.
- American Thoracic Society. Vitamin D Levels Linked To Asthma Severity. Medical News Today. MediLexicon, Intl., 2009 April 24.
- Journal Of Neurology Neurosurgery And Psychiatry. Vitamin D May Have Key Role In Helping Brain Work Well In Later Life. Medical News Today. MediLexicon, Intl., 2009 May 21.
- Aaron Lohr. Link Between Successful Weight Loss And Vitamin D Levels. Medical News Today. MediLexicon, Intl., 2009 June 13.
- Hayes, Daniel. Vitamin D As Radiation Protection. Medical News Today. MediLexicon, Intl., 2008 November 10.
- Rajakumar K. Vitamin D, cod-liver oil, sunlight, and rickets: a historical perspective. Pediatrics. 2003 Aug;112(2):e132-5.
†Results may vary. Information and statements made are for education purposes and are not intended to replace the advice of your doctor. If you have a severe medical condition or health concern, see your physician.