Wednesday, December 1, 2010

My Vitamin D Experiment

As you'll note from this picture, I'm not well-adapted to the sun. ;) 

My ancestors pretty clearly lived mostly in the woods in an area with little annual sunlight, and consumed a fair amount of wheat.

For years this has been my bane: any lengthy sun exposure, say an hour or more, would leave me roasted.  To top it off, I hate sunscreen.

So I developed an extensive collection of hats, and learned to wear long-sleeved shirts on hot days.

Then at the end of last winter I read this post by Stephan Guyenet:

"There's a mouse model of skin cancer called the Skh:HR-1 hairless mouse. When exposed to UV rays and/or topical carcinogens, these mice develop skin cancer just like humans (especially fair-skinned humans). Researchers have been studying the factors that determine their susceptibility to skin cancer, and fat is a dominant one. Specifically, their susceptibility to skin cancer is determined by the amount of linoleic acid in the diet."

He has a number of other posts on the joys of linoleic acid, which had prompted me in March to make a concerted effort to avoid linoleic acid, but this post sprung to mind one day in late March when we had a rare blue-bird day of skiing.  As usual I forgot to wear sunscreen.  My face was exposed for a good 6-7 hours not only to the sun, but to the suns' rays reflected off the snow.

This occurred to me that evening.  I turned to my wife, and I said, "Look at my face!"  "What", she said, "you look perfectly normal."  Exactly!  I was out in the sun all day, and I did not get burned.

Shortly afterward we went to Barefoot Ted's Barefoot Running Clinic in Central Park in New York City.  As usual, I "forgot" to bring sunscreen along.  Since the trees had not yet shown their leaves, my wife and I found ourselves standing in the early-spring sun for 2.5 hours.  That evening my wife pointed out the sunburn she had gotten, and I pointed out that I had not burned. 

To understand the significance of this, you need to realize that my wife is Colombian.  Unlike me, she gets nut-brown in the sun, a trait she has happily passed along to our children.  My tendency to become a lobster in the sun has been a constant cause of concern to her.

She was incredulous.  In our 13 years together, it had never once happened that she had burned and I had not.  Moreover, we were standing side-by-side together for the entire time.

My experiment with eliminating extraneous linoleic acid was going extremely well for other reasons, but this was a happy side-effect.

A month after Ted's clinic, we went to Disney World.  For five days we tromped around the Magic Kindom.  One afternoon my hands started to feel a bit tingly, so I put sunscreen on my hands and forearms.  But for the rest of the time, nothing.  Shirts, hats occasionally, and shorts, but no sunscreen.  And no burn.  I would get red, but then wake up more tan (for me) the following morning.  Pretty incredible.

So the summer continued, with me spending increasing amounts of time out in the sun with no sign of a sun burn.  People began to comment on the nice tan I was developing, and how blonde my hair had gotten.  This was entirely out of the ordinary.

I finally discovered what it took for my new skin to get a sunburn.  We went to Colorado in August, and I decided to spend a day running and hiking up and down Pike's Peak.  I spent about 9 hours in the sun at altitudes varying from 10,000 to 14,000 feet.  I finally got a sunburn.  The picture above is me the day after.  All of me got a bit pink, but the only part that really got "burnt" was the back of my calves.  They peeled, lightly, but nothing like what I would have expected to experience.

This would have been a fine day to actually wear sunscreen.  Anyone would have burnt after being in the sun for hours at altitude, but for me it was pretty incredible that I got only a "normal" burn.

My wife, who had been getting more and more prone to burning, was convinced by our experience at Ted's clinic to join me in my dietary experiment.  She has also recovered her ability to tan, although it happened more slowly than it did for me.

I call this post my vitamin D experiment because I had been taking D supplements for the previous winter.  After I figured out that I could stand the sun, I decided to stop taking them, and see if I could, through regular sun exposure, get my D levels up to something approximating "normal" through sun alone.  That experiment was also a success.

And I'm not the only one who's experienced this phenomenon:

"9. Near-immunity to sunburn. Throughout my life, a half-hour’s direct sun exposure left my skin looking and feeling like it had been scalded with boiling water, and it took weeks to recover. Now, I spend hours in the sun shirtless without even a patch of tender skin afterwards. I can only conclude my body has become orders of magnitude better at protecting and repairing tissue. To me, this suggests many startling implications, not least among them the prevention of cancer and senescence."