Thursday, June 6, 2013

Sunscreen {a historical perspective}

I've always thought that sunscreen smells bad, feels bad, and is just generally inconvenient. Since I also know that vitamin D is important for many reasons, and your body synthesizes it from the sun, I generally use the excuse of “getting my vitamin D” for not applying sunscreen as often or as liberally as recommended.

Since sunscreen season is fully upon us, I thought a post (or perhaps a series of posts)
looking at what the evidence has to say about sunscreen would be timely. Today we’ll start with a historical perspective.

In The Five Paradoxes of Vitamin D and the Importance of Sunscreen Protection, Russell Chesney takes time to look at the history and relationship between vitamin D and sunshine. Below is a short summary and review of his journal article published in Clinical Pediatrics.

Rickets, a vitamin D deficiency disorder, first emerged in England around the start of the industrial revolution and reached epidemic proportions by 1650. At first, it was puzzling that rickets was much less prevalent in the tropics and in rural areas, but as the link between vitamin D and rickets and the sources of vitamin D became known, this observation made sense. By 1930, it was well understood that vitamin D deficiency caused rickets and that there were 2 “sources” of vitamin D, a substance found in cod liver oil, and sunshine. Due to the nature of extreme latitudes, the coal in the air above cities to filter the sunlight, and the habits of city dwellers, it made sense that those who lived in cities would receive less sunlight, and therefore be more susceptible to vitamin D deficiency and rickets.

In 1931, The Children’s Bureau strongly advised parents to suntan infants and give them cod liver oil. At this time in history, the value of sunlight exposure was highly stressed, while there was little thought given to potential skin damage. (How far we have swung to the other side, when we now recommend little to no sun exposure for the first 6 months!)

Around 1985 it was observed that skin cancer rates were increasing. With this observation came the real fear of developing skin cancer from exposure to sunlight. Sun exposure recommendations therefore changed, and today the AAP and the American Academy of Dermatology recommend shelter form sun and liberal sunscreen use. However, adhering to these recommendations necessitates vitamin D supplementation by mouth in order to prevent deficiency.

It is interesting to me, but not surprising, that opinions of whether vitamin D should be absorbed from the sun or ingested through diet/supplements are highly influenced by the current opinion concerning the potential harmfulness of the sun.

It’s estimated that a large percentage of the United States is vitamin D deficient, and I’m curious if this could be related to our sun protection behaviors. Also, is there any reason that the sun might be stronger today and consequently require more “protection” from than in the past? Or is this obsession with sun protection just a result of our safety obsessed society? Next week, I hope to address some of these questions.

But enough of me talking, what is your relationship to sunscreen? Do you practically hate it too?

Chesney, RW. The five paradoxes of vitamin D and the importance of sunscreen protection. Clin Pediatr (Phila). 2012 Sep;51(9):819-27. doi: 10.1177/0009922811431161. Epub 2011 Dec 12. Accessed on 6/3/13.

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