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Vitamin D: "The Sunshine Vitamin" Meets Sunscreen

Vitamin D: "The Sunshine Vitamin" Meets Sunscreen
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Summertime.   After a spring with some much-needed rain in theNortheastern U.S., we are turning our thoughts to sunny days at parks, playgrounds, beaches and pools.  The promise of warm sunshine on our skin seems soothing but also provokes worries about sun overexposure and risk of skin cancer.  A new study on vitamin D and sunscreen furthers our understanding of how so many of us have become deficient.

 

In Denmark, researchers evaluated the relationship between the amount of sunscreen applied and vitamin D levels after controlled UV light exposure (Faurschou A, et al: The relation between sunscreen layer thickness and vitamin D production after UVB exposure - a randomised clinical trial. Br J Dermatol. 2012 Apr 18. doi: 10.1111/j.1365-2133.2012.11004.x. [Epub ahead of print]).  37 healthy volunteers with fair skin types were randomized to one of 5 groups, having specific thicknesses of SPF 8 sunscreen (0 mg/cm2, 0.5 mg/cm2, 1 mg/cm2, 1.5 mg/cm2, or 2 mg/cm2) applied to their upper bodies (approximately 25% body area). 20 minutes after sunscreen application, participants were irradiated with a fixed UVB dose.  This procedure was repeated four times over a 1-2 week period.  Vitamin D levels (25-OH D) were drawn before the first irradiation and three days after the last treatment for comparison.  What happened?  The vitamin D level increased in an exponential manner with decreasing thickness of sunscreen layer in response to UVB irradiation, up until the maximal thickness of 2mg/cm2 was applied.  There was no significant vitamin D increase with irradiation at that thickness. 

 

What is the clinical meaning of these findings?   The authors noted that they studied an SPF of 8 and a thickness of 2mg/cm2  based on current recommendations by the World Health Organization (WHO).  Furthermore, most sunscreens are actually tested for efficacy in laboratories at – you guessed it – a thickness of 2mg/cm2.  While many people in real life probably don’t apply sunscreen at the recommended and tested thickness, they do typically use sunscreens with higher SPF’s (15 to 30 minimum), especially for kids, blocking even a greater percentage of UV rays. 

 

What is one to do?  Some sun exposure without sunscreen is likely to be of benefit without increasing risk of skin cancer.  But how much?  In what part of the world?  For which people?  These are all questions that need to be studied.  Until then, most people will need to rely on supplemental sources of vitamin D for optimal health.

If you are looking for the safest chemical-free sunscreens, the Environmental Working Group recently updated its handy Sunscreen Guide for 2012.

 (http://breakingnews.ewg.org/2012sunscreen/)

 

srosenLawrence D. Rosen, MD is a board-certified general pediatrician committed to family-centered, holistic child health care. He practices primary care at the Whole Child Center in Oradell, NJ and consults at the Joseph M. Sanzari Children's Hospital at Hackensack University Medical Center, serving as Medical Advisor to The Deirdre Imus Environmental Health Center.  

 Dr. Rosen is an internationally recognized expert in Pediatric Integrative Medicine.  He is a founding member and Chair of the American Academy of Pediatrics Section on Integrative Medicine.  Dr. Rosen is appointed as Clinical Assistant Professor in Pediatrics at New Jersey Medical School. He is a graduate of New York Medical College and the Massachusetts Institute of Technology, and he completed his residency and chief residency in pediatrics at Mount Sinai Hospital in New York.  

 Dr. Rosen is a contributing author/editor for several books, including “Integrative Pediatrics” (Oxford University Press 2009), “Green Baby" (DK 2008), and "Pediatric Clinics of North America: Complementary and Alternative Medicine" (Elsevier 2007).  He is a contributing editor and pediatric columnist for Kiwi magazine.

 

 

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