Vitamin D Source Sun

Vitamin D is sometimes known as the “sunshine vitamin.” That’s because your body makes vitamin D when it’s exposed to sunlight. In fact, vitamin D is the only vitamin that your body is able to manufacture itself-but it needs the help of the sun to do so.

Sun exposure is the easiest way for most people to get vitamin D. However, many people don’t know how much time they need to spend in the sun to get the vitamin D they need, or they aren’t able to spend much time in the sun. As a result, many individuals have low vitamin D levels.

Vitamin D, the Sun and Your Health

Your body makes vitamin D when your skin is exposed to the UVB rays in sunlight. In some parts of the world, people get enough sun exposure to be able to make vitamin D year round. However, people who live above about 42 degrees north latitude often don’t get enough sunlight to make vitamin D during winter months.

Other factors can also influence the amount of vitamin D you can get from the sun. Total cloud cover, for example, can reduce vitamin D production by about 50 percent. Sunscreen with a SPF greater than 8 also seems to inhibit the production of vitamin D. However, most people do not apply enough sunscreen to completely cover their skin, apply sunscreen unevenly, or fail to reapply sunscreen at regular intervals. These factors are likely to allow some vitamin D production in people who wear sunscreen.

In addition, UVB rays do not penetrate glass, so you must be outside in order to get vitamin D through sun exposure. Time of day, shade smog can also affect vitamin D production.

How Much Sun Is Enough?

There is no clear consensus on how much time you need to spend in the sun to maintain adequate vitamin D levels. Exposing your face, arms, legs or back to the sun without sunscreen for between 5 and 30 minutes of sun exposure in the middle of the say (between 10 am and 3 pm) about twice a week is recommended by some researchers. Some commercial tanning beds may emit UVB radiation, but there are other risks associated with using tanning beds.

Unfortunately, while sun exposure is an excellent way to get vitamin D, UV radiation is also associated with an increased risk of skin cancer (melanoma, for example). Exposure to sunlight is also associated with cosmetic changes (such as dryness) that many people may want to avoid. Many doctors recommend a combination of limited direct sun exposure for vitamin D production combined with sensible sun protection measures, such as sunscreen and protective clothing.


Kotz, D. (2008). Time in the sun: How much is needed for vitamin D? Retrieved December 27, 2009 from the US News