
The Sun. It fuels our world. It's essential to life. We need sunlight to make Vitamin D in our bodies, but the sun's radiation can also cause skin cancer. The challenge is find the right balance of sun exposure and sun protection.
Avoid the sun. Wear sunblock. That’s my summer mantra. Now that I’ve had some skin cancer removed, I’m even more paranoid about sun exposure.
The darkest time of the year is here, so you’d think I could relax about sun exposure as I enter my annual winter hermit state, covered up and shivering by the hearth. But no, I have a new worry: I actually have to get outside to get some sunshine to make Vitamin D.
Ten to 15 minutes of sunshine (ultraviolet B radiation) three times a week is supposed to be enough for most people, but this is tough in the winter when we’re swathed in fleece. I don’t even like to walk to the mailbox at the end of my driveway when it’s cold.
Vitamin D is a fat-soluble vitamin that helps the body absorb calcium to form strong bones and teeth and has many other important functions in keeping us healthy. My dermatologist says that Vitamin D is the hot topic at dermatology conferences these days. Yes, I know, we’ve all heard and read about the wonders and miracles of this vitamin and that vitamin, only to find out later that taking extra this or that doesn’t help and can even hurt. I still have a huge jar of Vitamin E capsules that I thought was supposed to be good for me. Then studies reported Vitamin E as a supplement could be harmful. Now I’m just hanging onto the almost-full bottle in case it comes back into favor. (By then, of course, if will be expired.)
Researchers are continually finding out more about the importance of Vitamin D, including that we probably need more than previously thought and that it’s even more essential to maintaining good health than we’ve realized.
Vitamin D could play a role in the prevention of colon, prostate and breast cancers, for example. The amounts in our bodies might affect our mood and our weight. Vitamin D really could be essential to a sunny disposition and important in keeping us from piling on the pounds.
Bottom line: Find out how much Vitamin D you need and get a little sunshine at least every other day.
The following information can get a little tedious, but it’s important, so pay attention.

You need sunshine, but not as much as the people in the posters are getting. This woman is probably getting enough as she walks past posters on a tanning salon while walking from her home in the Seattle area to the grocery store on Dec. 22, 2008. (AP Photo/Seattle Post-Intelligencer, Andy Rogers)
A multi-vitamin with Vitamin D is probably enough for most people, but one size doesn’t fit all. As you get older, your body isn’t as efficient at making Vitamin D, so you’ll need more Vitamin D in your diet, usually as an additive or a supplement. My dermatologist told me to get 1,000 units of Vitamin D and a little sunlight (UV-B) every day, but you need to check with your own physician for the right amount for you. (See link below to article about children’s need for Vitamin D.)
Vitamin D isn’t naturally present in most foods, although it’s added to milk and cereal. It’s in fish, such as salmon and tuna, in egg yolks and in cheese. It’s also in cod liver oil, which is why we heard stories of a spoonful of it being forced on children in the past.
There’s also a danger of getting too much, which can cause increased kidney stones, nausea and mental confusion. Vitamin D is stored in the fat, so if you take excessive amounts it’s difficult to get rid of.
We have to find a balance in protecting our skin from sun damage with the need for sunlight to synthesize Vitamin D. The darker your skin, the more sunlight you need to make Vitamin D. One of my biology professors suggested that Vitamin D is so important that it’s probably the main reason for differences in skin color. The closer you to to the poles, the more difficult it is to get enough sunlight to make Vitamin D. Conversely, darker skin protects against sun damage.
People with higher skin melanin (pigment) content require more time in sunlight to produce the same amount of vitamin D as do people with lower melanin content. As noted below, the amount of time a person requires to produce a given amount of Vitamin D may also depend upon the person’s distance from the equator and on the season of the year.

These people have the right idea. Get outside in the winter, even if it's cloudy and snowy. Just don't get frostbitten or sunburned. I need to take my own advice, because I don't even like to go to the mailbox when it's cold.
Latitude and altitude determine the intensity of UV light. UV-B is stronger at higher altitudes. Latitudes higher than 30° (both north and south) have insufficient UV-B sunlight two to six months of the year, even at midday, according to researchers. Latitudes higher than 40° have insufficient sunlight to achieve optimum levels of D during six to eight months of the year. In much of the United States, which is between 30° and 45° latitude, six months or more during each year have insufficient UV-B sunlight to produce optimal D levels. In far northern or southern locations, latitudes 45° and higher, even summer sun is too weak to provide optimum levels of vitamin D. A simple meter is available to determine UV-B levels where you live.
It’s a complicated, but important, subject. To read more, here are some websites and articles:
NEW: What do you lack? Probably Vitamin D. (New York Times article)