What’s up with Vitamin D?!

Vitamin D has been getting a lot of hype lately.  It’s been in the news, docs are talking about it, and we at Student Health Services even offer an OIY (Order it Yourself) Vitamin D test.  Vitamin D is something that is made by our bodies from the sun, so why is there all this talk about vitamin D deficiencies?

It turns out that living in Ohio is not very conducive for vitamin D production, at least not in the colder months.  The amount of vitamin D you can get from exposing your bare skin to the sun depends upon 4 factors:

  • Time of day
  • Where you live
  • Color of your skin
  • Amount of exposed skin

Time of Day:  Think of the whole sun rising in the east and setting in the west thing.  When the sun is rising and setting it’s coming at us from an angle and it turns out that is not a good thing as far as vitamin D goes.  When the sun is angled the atmosphere blocks the UVB part of the rays which are what produces vitamin D.  The closer to midday the better the angle and the more vitamin D.

Where you live:  The closer to the equator the easier is it to produce vitamin D.  Again back to the angle thing – the further from the equator the greater the angle and the less UVB exposure.

So, consider Ohio in the winter.  Yeah.  Far from the equator and the sun is almost always angled which means rarely is there an opportunity for UVB exposure.

Color of your skin:  Melanin in our skin protects us from skin damage from too much UVB exposure.  As a result darker skin with more melanin allows less UVB to enter the skin, meaning less vitamin D is produced.  The darker the skin, the more time that must be spent in the sun to product vitamin D.

Amount of exposed skin:  It’s going to take a lot longer to made vitamin D if just your face and arms are exposed than if your back is exposed.

OK, so putting this all together, and assuming that 25% of your skin is exposed and its summer in Ohio, an individual with pale skin that tans fairly easily would need approximately 1 hour of exposure to the sun during midday to produce 1,000 IU.  An individual with dark skin would need approximately 2 hours of exposure to produce the same amount.  During the winter, it’s not possible to make vitamin D, regardless of skin type.

Oh and if you’re thinking that you can hang out in a nice air conditioned sun room and get your vitamin D through the glass – forget it!  Glass blocks all UVB.

So, how much vitamin D do you need?  The institute of Medicine recommends that adults ages 19-70 get 600 IU daily.  Not a problem if you spend time outside during the summer, but what to do in the winter?  Vitamin D can be obtained from foods, but it’s nearly impossible to get enough.  Foods that contain vitamin D are:

  • Fatty fish
  • Beef liver
  • Egg yolks
  • Fortified milk and orange juice
  • Fortified cereals

The only other option is supplements.  If you choose to take a supplement make sure that it is D3, not D2.  D3 is what would be produced by your body when exposed to sunlight.  The amount to take varies depending on where you look, but a good rule of thumb is 600 IU daily. 

If you have concerns about your vitamin D or believe that you might be deficient, come see us at Student Health or schedule an appointment with your primary care provider.  They can test your vitamin D levels and direct you as to your best course of action.

For more information on Vitamin D, check out the Vitamin D Council website.

Submitted by Tina Comston, M.Ed.

Reviewed by Mary Lynn Kiacz, M.D.