Washing away vitamin D

Posted on January 31, 2012 by John Cannell, MD

The recent Netherlands paper on “natural” vitamin D levels in Africa immediately brought to my mind another paper, a similar attempt to gather this vital information. If we don’t know what our vitamin D levels were during the two million years our species was evolving, then how do we know what level to achieve while we wait for science to complete its work?

Binkley N, et al. Low vitamin D status despite abundant sun exposure. J Clin Endocrinol Metab. 2007 Jun;92(6):2130-5. Epub 2007 Apr 10.

Professor Binkley and his colleagues found that surfers and skate-boarders in Hawaii had levels around 30 ng/ml with the highest level being 60 ng/ml. Why would light-skinned sun-drenched outdoor sport enthusiasts in Hawaii have an average level of 30 ng/ml, while very dark-skinned hunter-gatherers in Africa have levels of 50 ng/ml?

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About John Cannell, MD

Dr. John Cannell is founder of the Vitamin D Council. He has written many peer-reviewed papers on vitamin D and speaks frequently across the United States on the subject. Dr. Cannell holds an M.D. and has served the medical field as a general practitioner, itinerant emergency physician, and psychiatrist.
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9 Responses to Washing away vitamin D

  1. roger.rolfe@sympatico.ca said on January 31, 2012 at 9:17 am

    This blog post is cut off with an ominous warning “Sorry but you do not have access to this post/page. Please review your membership here No access.”. I’m sure my membership is up to date, and I can access every other blog post. Please clarify.

  2. roger.rolfe@sympatico.ca said on January 31, 2012 at 11:03 am

    Thanks for fixing your technical problem. It works fine now.

  3. Brant Cebulla said on January 31, 2012 at 11:05 am

    Issue is fixed, thanks Roger.

  4. cwnielson said on February 1, 2012 at 4:55 am

    Is it possible surfing itself washes off the relevant oils?

  5. Brant Cebulla said on February 2, 2012 at 10:09 am

    This is a question of mine as well, cwnielson.

  6. Frederica Huxley said on February 8, 2012 at 1:48 pm

    This begs the question – how long does it take for the skin to absorb the precursor to Vitamin D? 12 hrs, 24hrs, or days?

  7. Brant Cebulla said on February 9, 2012 at 1:05 pm

    Frederica,

    Skin first produces previtamin D3 in plasma membranes of skin cells, and about 50% of this previtamin D3 is converted to vitamin D3 within 2 hours.

    Holick M. “Photobiology of Vitamin D” Vitamin D: Second Edition, Chapter 3. 2005.

    Body begins converting vitamin D3 from the skin to 25(OH)D at 10 hours, with 25(OH)D levels peaking at 24 hours.

    http://www.ncbi.nlm.nih.gov/pubmed/8390483

    This second paper is a great read, highly recommend, and it is open access.

  8. donnafickel said on February 9, 2012 at 6:07 pm

    Thanks Brant for clarifying the time period. Perhaps a 24 wait before taking a shower after a therapeutic sun bath is ok?

  9. eelisabethpuur@gmail.com said on March 1, 2012 at 3:12 pm

    Being a dogowner all my life, I have to ask; when I´ve been out in the sun all day, (remember that Sweden has too little of summermonths with sun) … the sun is shining, it´s just fantastic, you really feel “sun-kissed” and blessed, and the skin has a film of sweat, what happens? the dogs always came and licked the sweat away. I thought it was about the salt, for many years, but now I think it might be the vitamin D. What do you say?

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