Shedding light on Vitamin D

Sunset and Storm Clouds Over Skagit Bay

Get MedInfo in your inbox

We'll send you a notice when we publish new stories.


Gloomy winter skies are the norm here in the Pacific Northwest. And since no sun means no Vitamin D – the “sunshine vitamin” — we should all be downing high doses of Vitamin D supplements, right?

Not so fast, says Dr. Andre Zand, a board-certified internal medicine doctor at Northwest Primary Care Richmond Beach Clinic. “Just because we don’t see the sun for days at a time doesn’t necessarily mean we should stress about our Vitamin D levels,” he said.

Vitamin D is essential for bone and muscle health. It helps the body absorb calcium and phosphorus, promotes bone health and reduces the risk of fractures.

But before we all request blood tests from our doctor and stock up on supplements, here’s some information to keep in mind as we wait for the sun’s return.

How do I get Vitamin D?

Your body absorbs Vitamin D when ultraviolet light, like that from the sun, strikes your skin. Your liver and kidneys then convert that Vitamin D into a form your body can use.

We can also get Vitamin D from a small group of foods, including fatty fish, fortified dairy products and eggs. Many people take daily multivitamins, which contain Vitamin D. And then there are over-the-counter supplements.

How much do I need?

Your daily needs depend on age. The recommended amount of Vitamin D for infants is 400 International Units (IU). For children and adults, it’s 600 IU. For adults older than 70, it’s 800 IU.

Even in the depths of winter, most adults can get those amounts without supplements, Zand said. “If people eat a healthy diet, maintain a healthy weight, and get outside regularly, they should have sufficient levels of Vitamin D.”

The sun might disappear for multiple days, but it returns eventually. Exposing your face and hands to the sun for roughly 15 minutes at least two times a week will help you meet your Vitamin D requirements, Zand said.

Severe Vitamin D deficiency is serious. It can lead to thin, brittle bones, a condition called rickets in children, and osteomalacia in adults. (These diseases are relatively rare in developed countries, Zand said.)

On the other hand, too much Vitamin D also can be unhealthy. It can cause high calcium levels, which increases the risk of kidney stones. One study noted an increased risk of bone fracture in patients treated with high doses of Vitamin D.

The solution: stay in the “just right” zone by getting outside often and eating a healthy diet.

How is deficiency diagnosed?

Zand doesn’t routinely check patients for Vitamin D levels. But he will order tests for the following categories: elderly adults with mobility issues, patients with malabsorption syndromes, chronic liver and kidney diseases, and anyone with osteoporosis or a history of low-trauma fracture.

Disagreements on D

Over the past few years, some research studies have suggested links between low Vitamin D levels and health issues like cardiac disease, multiple sclerosis, depression, immune disorders and some cancers. But the science is still out on whether supplements can prevent any of these issues, Zand says. “Experts don’t agree on any real connection between these health issues and taking supplements, and more research is needed.”

So scientists will continue to study Vitamin D’s role in our health. In the meantime, Zand says, focus on eating right and getting sun when you can, and you should be fine until the gray skies lift.

For more information about Northwest Primary Care or to make an appointment with Dr. Zand, visit or call 206-520-5000.

Share Tweet