Vit D - how much do you need

American Academy of Dermatology Issues Updated Position Statement on Vitamin D
Laurie Barclay, MD From Medscape Medical News

July 16, 2009 — The American Academy of Dermatology (AAD) has issued an updated position statement on vitamin D after reviewing more recent evidence regarding the role of vitamin D in maintaining optimal health. The National Council on Skin Care Prevention also released its own position statement on July 14.

Individuals who regularly and properly practice sun protection may be at risk for vitamin D insufficiency and may require a higher dose of vitamin D, either from dietary sources or from supplements. Because of skin cancer risk from ultraviolet (UV) radiation, AAD does not recommend unprotected exposure to radiation from the sun or from indoor tanning devices.

"The vitamin D position statement supports the Academy's long-held conviction on safe ways to get this important vitamin — through a healthy diet which incorporates foods naturally rich in vitamin D, vitamin D-fortified foods and beverages, and vitamin D supplements," dermatologist and AAD president David M. Pariser, MD, FAAD, said in a news release.

"The updated recommendation for individuals who practice daily sun protection acknowledges that while protecting the skin from the damaging rays of the sun is important, so is maintaining adequate vitamin D levels," Dr. Pariser said. "Concern about vitamin D should not lead people to forego sun protection, but rather prompt a conversation with their physician about how to ensure adequate and safe vitamin D intake while guarding against skin cancer."

In addition to individuals who protect themselves from sun or other UV exposure by daily use of sunscreen on exposed skin or by wearing sun-protective clothing, others at risk for vitamin D insufficiency include elderly individuals or those who have dark skin, photosensitivity, obesity, or fat malabsorption. These at-risk individuals should consult their physician regarding options for ensuring adequate vitamin D levels through dietary intake or supplement use, and physicians should be equipped to advise them properly.

Although serum vitamin D level (25-hydroxyvitamin D) can be easily measured and is a widely available blood test, further studies are required to identify appropriate serum concentrations of vitamin D needed for optimal health.

The standard reference now recommended by the AAD to advise patients regarding their needed minimum intake levels is the National Academy of Sciences Institute of Medicine guidelines for vitamin D. Because of new developments regarding knowledge of the clinical benefit of vitamin D, current recommendations for adequate vitamin D intake levels established by the Institute of Medicine may be increased in the near future.

The US Department of Agriculture Dietary Guidelines recommend that those at risk for vitamin D insufficiency receive supplementation with a total daily dose of 1000 IU vitamin D, according to the AAD statement.

The AAD recommends supplementation with 200 IU vitamin D from birth to age 50 years for those who are not at increased risk for vitamin D insufficiency. However, the American Academy of Pediatrics recommends supplementation with 400 IU vitamin D per day for children younger than 18 years of age, including infants.

Because vitamin D can be toxic in high doses, the US Food and Nutrition Board has set an upper limit for safety for vitamin D intake of 2000 IU per day for individuals older than 12 months of age and 1000 IU per day for infants.

For vitamin D supplementation, vitamin D3 (cholecalciferol), which is the form of vitamin D naturally produced in the skin, is preferred to vitamin D2 (ergocalciferol).

The updated AAD statement now emphasizes that there is no scientifically proven safe threshold for exposure to the sun or indoor tanning devices that optimizes vitamin D synthesis in the skin without increasing skin cancer risk. Laboratory research has shown that UV radiation from either the sun or tanning devices can cause oncogenic mutations in skin cells, and use of sunbeds has also been associated with increased risk for melanoma and squamous cell carcinoma. UV radiation exposure has also been linked to cataracts, premature aging, and immune suppression.

"It is well documented in the medical literature that unprotected exposure to UV radiation from natural sunlight or indoor tanning devices causes skin damage," Dr. Pariser said. "There is no current research available that provides a safe limit for sun exposure to maximize vitamin D production that does not put the individual's health at risk for developing skin cancer."

Low levels of vitamin D have been linked in numerous studies to greater risk for certain cancers and for some neurologic, autoimmune, and cardiovascular diseases, but clinical trials have not yet been performed to show a causal relationship of vitamin D to these diseases.

"Contrary to some reported information about vitamin D and the prevention of certain cancers and diseases — other than for bone health — we simply need more clinical data to determine what role, if any, vitamin D plays in these conditions," Dr. Pariser said.

The AAD still recommends avoiding use of tanning beds. The National Council on Skin Cancer Prevention recommends protection from UV exposure when outdoors by seeking the shade between 10 am and 4 pm whenever possible, generously applying sunscreen with a sun protection factor of at least 15, and wearing sun-protective clothing, including wide-brimmed hats, long sleeves, pants, and UV-protective sunglasses.

"For those who are concerned about vitamin D insufficiency, diet and vitamin D supplementation are the most appropriate methods to obtain adequate vitamin D — it is not appropriate to seek exposure to ultraviolet radiation," said National Council on Skin Cancer Prevention co-chair Henry Lim, MD, FAAD, chairman of dermatology at Henry Ford Hospital in Detroit, Michigan.