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As the days get shorter, it’s time to say goodbye to the sun ... and one of our biggest sources of vitamin D.
The sun typically helps your body produce all the vitamin D you need, or at least close enough that you can get the rest through your diet. But living in the Pacific Northwest during the fall and winter months makes that hard (hello, Big Dark).
Vitamin D isn’t only needed to help you build strong bones — it’s also crucial for your immune system and your muscles. Here’s what you need to know about getting enough vitamin D during a PNW winter.
How you get vitamin D from the sun
The sun emits two types of ultraviolet rays that reach the Earth: UVA (long-wave) and UVB (short-wave). UVA rays penetrate your skin more deeply. UVB rays, on the other hand, help your body make vitamin D. But getting the vitamin D you need isn’t quite as simple as stepping outside.
In the winter — especially in northern latitudes — the sun never gets high enough in the sky for UVB rays to penetrate the atmosphere and reach your skin. That means you can’t rely on the sun from about September to March to give you the vitamin D you need if you live in a place like the Pacific Northwest. Plus, cloud cover can also reduce vitamin D production during these rainy winter months.
Why you need vitamin D
When there’s less sunlight and, in turn, less vitamin D production, it can impact your health. Your body needs enough vitamin D production to absorb and retain enough calcium, which promotes strong bones and teeth. Plus, vitamin D plays a role in strengthening your immune system and may help with mood regulation.
Vitamin D deficiency can affect mental health, too, from seasonal affective disorder to noticeable effects on already-existing depression. This is especially relevant during The Big Dark.
And if you’re diagnosed with breast cancer or prostate cancer, your chances of survival may be lower than those of someone with normal vitamin D levels.
Some people are more likely than others not to have enough vitamin D, including those with conditions that prevent them from going outside, such as neurological disorders, dementia and heart disease. Additionally, people with conditions like osteoporosis, chronic kidney disease, liver failure and inflammatory bowel diseases also have an increased risk of being deficient. So do Black and Hispanic children and adults, older adults with a history of falls or nontraumatic fractures, and obese children and adults.
How to know if you need more vitamin D
Simon Hsu, MD, a nephrologist at UW Medical Center – Montlake, says it’s especially important to ask your doctor to get your vitamin D levels checked if you have any health conditions that might put you at risk for a vitamin D deficiency. A simple blood test can give you the information you need, like if you need a supplement or not.
Hsu says that the main way people find out about an undiagnosed vitamin D deficiency is by fracturing a bone.
“Vitamin D deficiency is largely asymptomatic until someone breaks a bone, so it’s important to ask your doctor to get screened if you have any of these risk factors or health conditions,” Hsu says.
However, Hsu says that many large clinical trials of vitamin D supplementation show that most people without risk factors for vitamin D deficiency have enough vitamin D in their bodies to keep them healthy — another reason why it’s important to check before jumping to a supplement.
3 ways to get vitamin D this winter
According to Hsu, there are only three ways to get vitamin D: sunlight exposure, food and supplements. Here’s what you need to know about each one.
How to get vitamin D from food
Sunny days aside, you can also get vitamin D from food, but the options are limited.
“Very few foods naturally have vitamin D — fatty fish, mushrooms and eggs, and that’s it,” says Hsu.
Some foods like milk and orange juice may be fortified with vitamin D, but if you have a deficiency, food sources are likely not to provide enough vitamin D.
Because of this, Hsu typically recommends supplements for people who are vitamin D deficient.
How to get vitamin D from sunlight in the winter
When you don’t want to spend time outside during a rainy PNW day, using phototherapy, or light therapy, can be a quick and easy way to get some vitamin D from light without leaving your house.
However, for many people, taking a vitamin D supplement might be safer than using a light box that emits UV rays. If you’re looking for a way to combat seasonal affective disorder, though, UV-free light boxes, aka “therapy lamps,” can still be a useful way to do so.
If there is a rare break in the clouds, Hsu says the recommended amount of sun exposure for most people is about 15 to 30 minutes to the face and arms two to three times a week.
How to get vitamin D from supplements
With so many supplements on the market, it’s first important to understand how much vitamin D you actually need. Hsu says that, for most, having vitamin D levels between 20 and 30 ng/mL is enough to keep you healthy.
When looking for supplements, a product that contains D3 could be more beneficial.
Vitamin D3 raises your vitamin D level more than D2, although both work and can be used to treat vitamin D deficiency.
The amount a person needs will vary depending on why they are vitamin D deficient, says Hsu, so it’s important to ask your doctor to recheck your vitamin D level three to four months after starting supplementation to make sure your vitamin D level is improving.
If you are very deficient in vitamin D, your doctor may suggest a supplement with more than 4,000 IU per day for a short period of time to boost your level quickly. This should be monitored closely with follow-up blood tests to ensure the vitamin D circulating in your blood doesn’t reach toxic levels.
Signs of vitamin D toxicity, which is rare, include nausea, vomiting, a metallic taste in your mouth, headaches and body aches. It can also lead to pancreatitis and calcification in the kidneys and blood vessels.
For optimal bone health, pair your vitamin D supplement with 1,000 milligrams of calcium per day, either through diet or a combination of diet and supplements.
Keep in mind: If you’re taking a daily multivitamin, any vitamin D in that supplement should be included in your daily dose.
Remember: supplements are only helpful if you’re deficient
“The majority of people without risk factors for vitamin D deficiency are vitamin D sufficient, and there is no additional benefit of vitamin supplementation,” Hsu says.
That’s why, even though vitamin D deficiencies are more common here in the Pacific Northwest, it’s important to check in with your doctor before starting any supplements. And until the summer returns, find the light where you can.
This article was originally published on Nov. 27, 2017, by Kristen Domonell. It has been reviewed and updated with new info. Ari Cofer contributed to this article.
