Sunlight not necessarily best way to get Vitamin D

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Vitamin D is important for the metabolism of calcium and phosphorus. Its deficiency was linked to rickets in children and osteomalacia in adults, diseases now almost unknown in the developed world.

The vitamin is added to milk, orange juice and other foods to prevent possible deficiencies. Vitamin D is important for maintaining healthy and strong bones and muscles. More recent research has shown that it is also important for the prevention of cardiovascular diseases and colorectal cancer as well as for maintaining a balanced immune system.

The major source of Vitamin D is the skin exposed to sunlight or other artificial sources of ultraviolet B radiation. This radiation leads to the synthesis of the biologically active form of the vitamin -- Vitamin D3 or calcitriol.

Unfortunately, ultraviolet B radiation is also absorbed by the DNA of certain skin cells, and can cause mutations that can lead to the development of malignant melanoma and other skin cancers. This explains why most doctors and dermatologists in particular recommend using sunscreens when spending time in the sun.

So, we need Vitamin D to prevent osteoporosis, colorectal cancer and cardiovascular diseases but when we get it by exposing our skin to sunlight we put ourselves at risk of developing skin cancers. This issue could be resolved very simply by increasing the amount of Vitamin D in our diet by supplementing it with easily obtainable preparations of this vitamin.

How much should a normal, adult person take? The dose normally recommended and still present in most multivitamins preparations is 400 units per day. This recommendation was based on studies done to define the dose necessary to prevent rickets. More recent studies have revealed that most people, especially those living at northern latitudes, need much higher doses of Vitamin D. Recently the American Academy of Dermatology has updated its recommendations for the Vitamin D intake by increasing it to 1,000 IU (international units) per day. Other experts recommend to supplement up to 4,000 IU per day.

The right amount of supplemental Vitamin D may, perhaps, lie in the middle. And as for sun exposure, we should continue to protect our skin from the harmful effects of ultraviolet radiation by using frequent sunscreen applications and avoiding any form of artificial tanning.

Francesco D'Alessandro, M.D., Ph.D., is a dermatologist at the Walla Walla Clinic.

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