Are You Getting Enough Vitamin D?

Dr. R. Preston Lamberton, Director of Endocrine Services at the Joslin Diabetes Center affiliate at Lawrence & Memorial Hospital, says “We are particularly prone to vitamin D deficiency due to the long winters with reduced sunlight exposure.”

by Dr. R. Preston Lamberton

Vitamin D deficiency has recently been described as a world wide epidemic that includes those living in the United States.  Over the past several years, it has been suggested that vitamin D deficiency may contribute not only to bone disorders such as osteoporosis, but also to a variety of other health concerns.  Living in New England, we are particularly prone to vitamin D deficiency due to the long winters with reduced sunlight exposure.  As a result, vitamin D deficiency is a potential concern to all those living in Connecticut and Rhode Island.

Vitamin D is classified as a fat soluble vitamin meaning dietary fat is required for its absorption from the GI tract.  It turns out that vitamin D is actually a hormone in regards to its chemical structure and how it acts in the body.  We get vitamin D either from foods fortified with vitamin D or foods naturally containing vitamin D, vitamin D supplements, or from sunlight exposure which leads to the production of vitamin D in the skin.

Years ago, it was thought that vitamin D only affected bone health and the absorption of calcium from the intestine.  It is now clear however that vitamin D has important actions, for example, on muscle function, skin, the immune system, breast tissue, the lungs, the pancreas and the liver.  Because of these diverse actions, vitamin D deficiency has been suggested to be involved in many serious diseases such as diabetes mellitus, multiple sclerosis, various cancers, and heart disease.  In addition recent studies have shown that low vitamin D levels in elderly patients may lead to muscle weakness, falls and hip fractures.  Vitamin D supplements can improve muscle function in these patients reducing the incidence of falls and hip fractures.

Vitamin D deficiency was perhaps first recognized as a widespread problem in the U.S. in 1988 based on an article published in the New England Journal of Medicine.  Since then many epidemiological studies have documented and better defined the prevelance of vitamin D deficiency.  It has been estimated for example that over fifty percent (50%) of those living in the Northeast have significant vitamin D deficiency that could negatively affect their health.  There are several reasons why vitamin D deficiency has become so common.  Relatively low amounts of vitamin D supplements are added to fortified foods making it very difficult to maintain adequate vitamin D levels through diet alone. The second reason for worsening vitamin D deficiency involves the more frequent (appropriate) use of sunscreens that block ultraviolet sunlight on the skin, leading to reduced skin production of vitamin D.

Most local health care providers have been very aware of the concern for vitamin D deficiency, especially as a result of the many medical publications addressing this issue.  Vitamin D deficiency can be diagnosed on the basis of a blood test measuring 25-vitamin D.  Once diagnosed, the treatment of vitamin D deficiency usually involves the patient taking vitamin D supplements, either by prescription or by using over the counter vitamin D.  Although the FDA has recommended a daily intake of 400 to 800 international units (I.U.) it is widely recognized that much higher vitamin D intakes should be recommended.  Most experts in the field now recommend 1000 to 2000 I.U. (or more) each day.

Another way to improve vitamin d levels is through limited careful sunlight exposure.  Studies have shown that for many patients 10 to 15 minutes of sun exposure to uncovered arms and legs twice a week may improve vitamin D levels.  To be effective, the sun exposure needs to occur between the hours of 10am and 3pm during the late spring through early autumn.  Some patients however, such as the elderly or those with darkly pigmented skin, will not make significant vitamin D in their skin despite sunlight exposure.  As a result these individuals are among those at highest risk for severe vitamin D deficiency.

At the present time, it is clear that patients and their health care providers need to continue to be aware of the risks for and the consequences of vitamin D deficiency.  By reducing the frequency of vitamin D deficiency, it is likely that many common, serious health disorders may also lessen in frequency and or severity.  Thus it is certainly worth asking your health care provider if you may have a deficiency of vitamin D.

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