I was out at high noon (about 1:12 CDT) today, and may have made some Vitamin D in my exposed skin. We had beautifully clear skies with cool, dry air and lots of sunshine. I did not use sun-block for the few minutes of skin cancer risk. Unfortunately, it was also only a few minutes of Vitamin D opportunity.
Ultraviolet light is attenuated and eventually blocked by the atmosphere. The lower the sun is on the horizon, the less UV light gets through. In Waterloo, IA we are entering the 7 months of the year when the sun is too low on the horizon. We do not get enough UV to produce any Vitamin D.
Less than half of Iowans, who do not take substantial Vitamin D3 supplements, have sufficient Vitamin D levels in September. By early April, that is less than 15%. My MN resident daughter bragged last week that she had gotten her 25-hydroxy Vitamin D level up to 34. The best she has ever been, but still lower than the 40 to 80 ng/ml goal. With 15 month old Gwen no longer stealing Calcium and Vitamin D3, Gwen’s mom needs to restock on both. So do most other people.
If you want to get “totally natural” Vitamin D from the sun this winter, you must go to Hawaii. Or you could ski, in shorts and tee shirt, above 10,000 ft elevation in Colorado or Utah. Frostbite!
Vitamin D3 is what we make when we can. Most of us need to take 2000 to 5000 units daily.
Take Control Naturally of your Bone Health by taking enough Vitamin D3 supplements.
Jay Ginther, MD