Myth: Vitamin D is Absorbed Through Glass

As you sit at work staring out the window, daydreaming about the beautiful warm weather outside, the sun shines into your office and it suddenly gets too hot. Oh wait! Never mind, It’s February in New York City, and the winter months are in full swing. With sub-zero temperatures and the blistering wind blowing, it is no wonder we hibernate indoors. Although it’s nice and cozy inside, there is one very important vitamin that you may be missing: Vitamin D.

It is now known that Vitamin D is absorbed through direct sunlight. In the summer months, most people normally get the recommended 10 minutes a day outside (even if it’s walking a few blocks to work), but through the months of November to March, most North Easterners opt to spend the minimum necessary time outdoors. Some of you might wonder if the sunlight that shines through your window is actually helping improve your Vitamin D levels. The answer is, No.  The New York Times released an article on Friday that addresses just this issue:

Sunlight consists of both ultraviolet A, or UVA, which penetrates deep within the skin layers and can cause premature aging; and ultraviolet B, or UVB, which causes the redness of sunburn. It’s the UVB rays that trigger the synthesis of vitamin D” writes Rabin. She then goes on to quote Dr. Michael Holick, a professor of medicine, physiology and biophysics at Boston University School of Medicine who says, “It doesn’t matter if it’s winter or summer, you will make no vitamin D sitting in front of a window — zip”.

Sad to say your beautiful bay windows are not helping with your Vitamin D absorption, but there are other ways to attain this nutrient. The Harvard School of Public Health Reports,

Few foods are naturally rich in vitamin D, so the biggest dietary sources of vitamin D are fortified foods and vitamin supplements. Good sources include dairy products, breakfast cereals (both of which are fortified with vitamin D)…[but] the best way to get enough vitamin D is taking a supplement.

So, if you don’t seem to be getting enough sunlight in the winter months like the most of us, be sure to consider supplementing yourself with Vitamin D. Recommendations of how much to take varies based on age, race, and baseline serum levels. The recommendations range from 800 to 1000 international units (20 to 25 micrograms) daily, but a doctor can test Vitamin D serum levels (of which can be helpful in attaining the optimal dose).

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