The Importance of Vitamin D
- September 06, 2011
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- Internal Medicine Blog
Vitamin D has been in the news a lot lately. It plays a major role in calcium absorption but recent research suggests it may do much more. Scientists have discovered vitamin D receptors on almost all tissues of the body meaning it may have a much larger effect on our health and development of disease than previously thought. This discovery has prompted increased interest in vitamin D and lots of buzz in the media about the potential benefits. First, it is important to understand where vitamin D comes from and if you may be at risk for deficiency.
Vitamin D is the only vitamin that is also a hormone. It is sometimes called the “sunshine” vitamin because it is synthesized in the skin from direct exposure to ultraviolet B rays. This process requires direct sun exposure; indirect rays or light through a window does not contribute. Ten to 15 minutes of sunshine three times a week can be sufficient to prevent deficiencies. Your body’s vitamin D production can be hindered by being further from the equator, air pollution, cloud cover, and sunscreen use.
If you have been told your vitamin D levels are a little low don’t worry – you are in good company. A lot of women in our area have insufficient or deficient levels of vitamin D. This could be due to our latitude, responsible use of sunscreen to protect our skin, tall city buildings blocking direct sun rays, and working long hours inside. Other risk factors for low levels of vitamin D include advanced age, obesity, and having darker skin.
Vitamin D also occurs naturally in a few foods such as fish, oysters, and eggs. Because of this limited representation in the typical American diet, many foods are fortified with vitamin D. Vitamin D is often added to milk and other dairy products, soy milk, and breakfast cereals. Sometimes this is not enough and you may need to add a vitamin D supplement. Recommended daily value for adults under 70 is 600 IU a day; those over 70 require around 800 IU a day. You may be directed by us to take a higher dose for a period of time if your levels are low. Safety research supports an upper limit of a dose of vitamin D to be 10,000 IU daily. This does not mean that you should take 10,000 IU a day but that doses above that may be harmful. A dose of 1,000 to 2,000 IU a day is much more reasonable. If you are purchasing a vitamin D supplement look for vitamin D3, or cholecalciferol, over vitamin D2, ergocalciferol.
We have known for some time about vitamin D's role in helping the body absorb calcium, in maintaining bone density, and in preventing osteoporosis. New research suggests it may also help protect against chronic diseases such as certain types of cancers, cardiovascular disease, high blood pressure, autoimmune diseases, and mood disorders. It is important to remember that further research is needed in these areas to confirm these associations and determine what the role of supplementation might be. There is a lot more work to be done in this area and taking mega-doses of vitamin D is not recommended and may be harmful.
