Vitamin D and Spring: More Sun, More D?

by Cal-EZ Team

Happy Spring everyone! Most of us in the United States have already set our clocks ahead one hour, and I think most of us will be glad to finally put Old Man Winter to rest and start enjoying the warmer weather and sunshine. I know I will.


Now that spring will officially be here tomorrow, what does that mean for our vitamin D levels? With the return of sunshine to our skin, our vitamin D levels should start to rise. Did you catch what I just said? Should.

Vitamin D and Spring

In spring and summer, the angle of incidence of the sun is smaller, meaning the sun’s rays strike the earth //">more directly than they do in //">winter. This results in a “stronger” sunlight for us in the Northern Hemisphere.



Vitamin D is made in the skin //">after exposure to UV-B rays, which is one type of UV radiation found in sunlight. The amount of sun exposure we’ll need for our skin to make vitamin D is around 15 minutes a day. Sounds easy enough to get 15 minutes of sun exposure a day, doesn’t it? But sometimes what seems easy is harder than you think.


We have been told to limit sun exposure and to apply sunscreen before going outside. The majority of sunscreens are broad spectrum, meaning that they block both UV-A and UV-B rays. Sunscreen use helps prevent sunburns and skin cancers, and, as an added benefit, may help reduce the rate of skin aging. But when we liberally apply sunscreen to our skin every day, we are further limiting the amount of UV rays reaching the skin.

Working and living indoors

Today, a majority of people spend a lot of time indoors. Our American culture finds us usually getting in our cars, driving to work, running into our jobsite, working all day, getting back in our cars, and driving home to start our evening routine. Even when not at work, we have so many ways to entertain ourselves at home opening our front doors may seem like a new adventure! How much time do we actually spend outdoors in the sunshine with our skin exposed to the sun? Probably not enough time to get our vitamin D production up.

The Window Quandary


Now, you may think even though you’re not in the great outdoors for 15 minutes each day, there are windows in our houses, cars, and workplaces that let sunshine in. In fact, there’s one certain window in our office building that I love to stand at in the winter because the bright sunshine warms me up. But did you know that with all the energy efficiency going on lately, that our windows do a great job of blocking UV-B rays? Yep, that’s right. So even though we can feel the sun’s warmth through our windows, we are still not able to produce vitamin D.

Just a note of caution. Just because windows do a great job of blocking UV-B rays, they //">do not block UV-A rays. UV-A rays also cause damage to the skin.


So what are we to do if we don’t spend enough time outside? According to the //">American Cancer Society and the //">Skin Cancer Foundation, we should all be getting our vitamin D from //">foods and vitamin D supplements.

For our other blog posts on vitamin D, //">click here.

For more information on vitamin D, download our vitamin D tip sheet.

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