The best way to get vitamin D? Time in the sun. (For Spectrum Health Beat)

Are you getting enough vitamin D? Unfortunately, the answer might be no.

In fact, about 40% of American adults are deficient in vitamin D.

That number rises to as much as 60% to 75% for elderly people and those with darker skin pigmentation.

“It’s important to make sure we’re getting enough,” said Krista Gast, a registered dietitian and certified health and wellness coach with the Spectrum Health Lifestyle & Culinary Medicine program.

“Many folks that live in areas like Michigan, where we don’t get enough sunlight during the winter months, are found to be deficient,” Gast said. “If you’re not able to get out in the sunlight every day for 15 minutes, then you’re likely to not have enough vitamin D.”

Why do we need vitamin D?

Vitamin D is important for many different health benefits—bone and muscle strength, heart health, as well as possibly reducing our risk of cancer, Type 2 diabetes, autoimmune diseases and more.

Vitamin D helps our bodies absorb calcium and it supports our immune system, too.

How much vitamin D do we need?

The recommended amounts vary, but the current recommended daily allowance for vitamin D is 600 international units per day for young adults and 800 IU per day for adults older than 70, Gast said.

How do we get vitamin D?

While our bodies are designed to get most of the vitamins we need primarily from food, vitamin D is a little different.

“The number one best way to get adequate vitamin D is sunlight,” Gast said. “We recommend 15 to 30 minutes of mid-day sun.”

That’s 15 minutes for people with lighter skin pigmentation and 30 minutes for people with darker skin pigmentation.

The reason? People with lighter skin have a lower concentration of melanin in their skin, so they produce vitamin D faster than people who have darker skin.

You can also get vitamin D from some food sources, including fatty fish like salmon, eggs and fortified foods like dairy products, orange juice, plant milks and cereals. There are even ultraviolet light-treated mushrooms that can add vitamin D to your diet, she said.

Because it’s challenging to get enough from food sources—and because sunlight is limited in certain climates and seasons—Gast recommends getting your vitamin D levels checked through a simple blood test your doctor can order.

If you’re low, you might need to take a vitamin D supplement.

Can you get too much vitamin D?

Yes. Vitamin D is a fat-soluble vitamin, as opposed to water-soluble. While our bodies can easily excrete an excess of water-soluble vitamins, that’s not the case for vitamin D and other fat-soluble vitamins. Instead, these can build up in our bodies and actually be toxic, although this is rare, Gast said.

The recommended safe upper limit is 4,000 IU per day, she said.

Can I get enough vitamin D without risk of sunburn or skin cancer?

Our bodies absorb vitamin D from the ultraviolet light from the sun, Gast said. They’re the same rays that can cause sunburn and skin cancer. So, of course, people must be careful.

But medical experts agree you don’t have to get a sunburn or even a tan to get vitamin D from the sun. In fact, you’ll likely absorb enough vitamin D in half the amount of time it takes for your skin to burn.

What should I do if I think I might be at risk of vitamin D deficiency?

If you suspect you’re low in vitamin D, talk with your doctor, Gast said.