Am I Getting Enough Vitamin D During the Winter?

While winter’s chill is in the air, you’ll likely need to look beyond the sun to satisfy your vitamin D needs, Dr. Young said. Foods that supply the highest amounts of naturally occurring vitamin D include fatty fish (like salmon, tuna and sardines), cod liver oil, beef liver, egg yolks and some mushrooms.

Many foods are fortified with vitamin D, such as milk, breakfast cereal, orange juice and yogurt.” She recommends supplements — especially in the winter — to get the full amount of vitamin D your body needs. “Vitamin D3 is the best supplement and comes in tablets and capsules, which you can take at any time of day.”

Fatty fish are perhaps the best: A 3-ounce salmon fillet delivers 71% of your daily intake, according to the National Institutes of Health (NIH). Other vitamin D–rich foods to eat in winter include mushrooms and egg yolks. But the easiest source of dietary vitamin D is often dairy.

As a result, the best way to get enough vitamin D is through the sunlight. “I recommend for people to get out for at least 15–20 minutes in the afternoon, so their bodies can absorb the sunlight.”

Vitamin D is a fat-soluble vitamin, meaning that it does not dissolve in water and is absorbed best in your bloodstream when paired with high fat foods ( 1 ). For this reason, it’s recommended to take vitamin D supplements with a meal to enhance absorption.

“Vitamin D3 cholecalciferol is the most absorbable and potent form, [whereas] Vitamin D2 (ergocalciferol) is typically plant-based and not as effective at raising vitamin D levels in the body and thus is not recommended as often,” she explains.

You don’t absorb enough vitamin D from food (a malabsorption problem) You don’t get enough exposure to sunlight. Your liver or kidneys cannot convert vitamin D to its active form in the body. You take medicines that interfere with your body’s ability to convert or absorb vitamin D.

There’s no set time of day that’s best to take vitamin D supplements. Some people say taking vitamin D supplements at night is an insomnia risk. There’s no research to confirm this, but you might want to take your supplement earlier in the day if you think it’s screwing with your sleep.

Yes, you can still get mood-lifting, immunity-boosting vitamin D on a cloudy day. Full-spectrum sun is still happening behind that gray, cloud cover and the ultraviolet needed to trigger the synthesis of vitamin D is still evident.

What About If I’m Wearing Clothes? A common misconception is that you can get vitamin D from the sun through clothing. This is not true, as the only way to trigger the chemical reaction that results in vitamin D production is for sunlight to reach your skin directly.

Generally, it takes a few weeks of taking daily vitamin D supplements for vitamin D levels in the body to rise. Each 1,000 IU of vitamin D3 taken daily is expected to raise blood levels of 25(OD)D by 10 ng/ml after a few weeks.