Vitamin D Intake for Winter Wellness
Longer Shadows Means Less Vitamin D Synthesis
It’s that time of year again, when a familiar chill creeps into the air, leaves change color and days get shorter. We all know that longer shadows mean winter is on its way. But did you know when your own shadow gets longer than you are tall, it’s a sign that your body is likely not making much vit. D?
That long shadow is a big deal because vitamin D is an important nutrient that helps support healthy bones, teeth, the immune system, and more.** Supplements can help sustain your Vit. D status throughout the winter, and may be especially helpful if you live up north.
Your body can produce Vit. D when your skin is directly exposed to sunlight (a.k.a ultraviolet radiation, or UV rays). But in the wintertime, the angle of the sun’s rays is lower. This indirect sunlight means shadows get longer, rays are scattered over a larger area, and less sunlight energy reaches the earth (and your skin!). Plus, the lower angle means sunlight passes through more of the earth’s ozone layer, enabling the ozone to absorb more of its energy.
This dwindling sunlight problem gets more pronounced as you move farther away from the equator. In fact, some research shows that during the months of November through February, in any territory above 37 degrees latitude (that line would pass through Virginia, the Kansas/Oklahoma border and Santa Cruz, California), there is an 80-100% reduction in the number of UVB rays that reach the earth.1
Of course, days get shorter, too – there’s less sunlight available. The bottom line: Residents of northern climates may have inadequate exposure to UV radiation in order to produce sufficient vitamin D. This lack of exposure to ultraviolet radiation may reduce vitamin D levels in the body, especially in winter.
So if you live up north, what can you do – besides moving to a sunny tropical paradise on the equator to boost your Vit. D in the winter? You can try dietary changes, but even the National Institutes of Health grudgingly admits, “Very few foods in nature contain vitamin D.” Those scant natural sources of vitamin D include cod liver oil, salmon and mackerel. Fortified foods usually provide most dietary vitamin D, and often include milk, cereal and orange juice.
Supplements are a great way to meet vitamin D recommendations when sunlight starts to dwindle. For men and women age 19-70, the Recommended Dietary Allowance of vitamin D is 600 IU (15 mcg). After age 70, RDA jumps to 800 IU (20 mcg). Many health experts, however, recommend a higher daily intake of Vit. D for optimal health benefits.
Up to 75% of teens and adults could use more D. If you think you’re among them, why not try a vitamin D supplement this winter? It’s like a ray of golden sunshine in your supplement cabinet!