Does Sunscreen Block Vitamin D? Here's What Health Experts Advise

And can you have a deficiency because of it?

Reviewed by Dietitian Maria Laura Haddad-Garcia

Vitamin D is called the sunshine vitamin for a reason. While we can get many essential vitamins and minerals from dietary sources, the main way we get this one is from sun exposure. Spend a few minutes underneath those warm rays, and your body will synthesize vitamin D. Not only is the sunshine vitamin beneficial for your immunity and even your mental health, but it’s also vital for your body’s production of calcium and keeping your bones strong.

Yet, shouldn’t you be worried about skin cancer if you expose yourself to the sun? Dermatologists always recommend protecting your skin with sunscreen, but will it affect vitamin D synthesis? Are we really stuck between picking one or the other?

In this article, we dive into the research and ask medical experts whether we should be worried about a vitamin D deficiency when using sunscreen.

Related: Can You Die from Vitamin D Intoxication? Here’s What the Science Says

What Is Vitamin D?

Vitamin D is a fat-soluble vitamin naturally found in some foods, like eggs and sardines, which your body can also produce when the skin is exposed to ultraviolet (UV) rays of sunlight. Vitamin D has two different forms: D2 (ergocalciferol), which comes from plant sources and fortified foods, and D3 (cholecalciferol), found in animal sources and produced by your body. Both forms are absorbed in the gut and have the same purpose, but the most effective and bioavailable form is vitamin D3.

This vitamin is vital because it promotes calcium absorption in the gut, which is key for bone health. Because your body cannot produce calcium naturally, if you’re not getting enough calcium and vitamin D through dietary sources (or, in the case of vitamin D, sunlight), the body starts to pull calcium from the bones, weakening them. So, adequate vitamin D levels are needed to keep our bones and teeth strong.

“Vitamin D is an essential nutrient for calcium absorption promotion and secondary function in reducing inflammation and sustaining immune function,” explains dermatologist Alain Michon, M.D., M.Sc., PG Dip Clinical Dermatology, medical director of Project Skin MD in Ottawa, Ontario.

While getting a sufficient amount of vitamin D at any age is important, it is particularly vital for children and for adults as they age. Children who are deficient in vitamin D are at risk of developing rickets, which creates weak bones and possible deformities. And because bone mass declines as you get older, having enough is also vital to avoid bone-related diseases such as osteomalacia.

Related: 8 Conditions When You Might Need a Vitamin D Supplement, According to Health Experts

How Is Vitamin D Produced in the Body?

A lot happens to your body when you’re exposed to the sun. When UV radiation penetrates through your skin, your body transforms a precursor of vitamin D into vitamin D3. Then, the liver converts that molecule into another type of vitamin D called 25-hydroxyvitamin D (calcidiol). And finally, the kidneys transform it into 1,25-dihydroxy vitamin D or (calcitriol), which is the active form of vitamin D. This molecule, which acts as a hormone, helps your body increase the absorption of calcium from the food you eat to strengthen your bones.

For this to happen, the average adult needs 5 to 30 minutes of unprotected skin exposure per day without the use of sunscreen to get a sufficient amount of vitamin D. However, many factors need to be considered when it’s time to (literally) soak up the sun: the season, time of day, skin color and weather since cloudy days and even smog could affect the amount of vitamin D you’re able to get. Experts say the best time of day to get sun exposure is from 10 a.m. to 4 p.m. daily (or at least twice a week) and to expose the skin on your face, arms, hands and legs.

Does Sunscreen Block Vitamin D Production?

Although getting enough vitamin D is important, too much UV radiation could increase the risk of developing skin cancers. UV exposure is associated with 80% to 90% of skin cancers, and the research continually shows that regular use of sunscreen is the key to reducing the risk of developing this type of cancer. But does this mean you’re not going to get enough vitamin D if you wear sunscreen?

Currently, there’s not enough evidence to show that sunscreen decreases vitamin D concentration, and researchers believe that it doesn’t cause vitamin D deficiency.  So, thankfully, this is not something you have to worry about.

While sunscreen can block UV rays, Michon says that in many cases, people fail to cover all of their skin when applying sunscreen or forget to reapply every two hours, as suggested by the American Academy of Dermatology. In these situations, people are likely getting the vitamin D they need, either from an unprotected patch of skin or because the sunscreen has worn off.

“Sunscreen reduces the amount of vitamin D you get overall, but not to the point where deficiency becomes a concern for most people,” he confirms. “Most sunscreen applications are not perfect, allowing some UVB rays to be absorbed by the skin.”

Protecting Your Skin While Maintaining Your Vitamin D Levels

According to Michon, you will likely get a good amount of vitamin D through natural sunlight even if you are applying sunscreen regularly because, again, sunscreen application is never perfect.

“Sunscreen is especially important on sunny days when you are moving around, sweating or swimming, as this can reduce efficiency and require more frequent application,” he recommends. “If you are lying on the beach, it is also important to use supplementary sun protection such as hats, sunglasses and breathable cover-ups to help protect the skin from direct sun exposure. Take breaks in the shade and stay hydrated as well, as the sun can quickly cause dehydration.”

Along with natural sunlight, Michon notes it's important to get vitamin D from other sources as well, such as your diet and doctor-recommended supplementation.

“I always encourage my clients to eat food high in vitamin D like fatty fish (salmon, halibut, mackerel), egg yolks, mushrooms and vitamin-D fortified foods like milk, cereal and oatmeal,” explains Gillean Barkyoumb, M.S., RDN. “In addition to these foods, I like to recommend vitamin D supplements because it can be difficult to get the right amounts needed every single day from diet and sun exposure alone.”

Should You Take a Vitamin D Supplement?

While there are some food sources that help you get some of this vitamin, in some cases, this might not be enough. The Recommended Dietary Allowances (RDAs) for vitamin D are 15 micrograms (600 international units) daily for people 19 to 50 years old, and adults over 70 should aim for 20 micrograms (800 IU). If you’re not sure if you’re getting enough and are considering supplementation, Barkyoumb suggests talking to your primary health care provider about testing your vitamin D levels and discussing with them whether a supplement is needed (and the right dose) based on your results.

The Bottom Line

Vitamin D is essential for overall health, including adequate calcium absorption (to keep bones strong), proper immune function and improved mood. The best sources of this fat-soluble vitamin are food, supplementation and sunlight. However, too much UV exposure may increase one’s risk of skin cancer, which is why dermatologists suggest always wearing sunscreen to protect the skin.

If you’re concerned about whether sunscreen blocks vitamin D absorption, experts and research say this may not be the case since the application of sunscreen isn’t always perfect, and people can still get enough vitamin D from the sun while wearing sunscreen. If you’re worried that you might have a vitamin D deficiency, talk to your doctor and take a blood test to learn about your levels and see if supplementation is necessary.

Read the original article on Eating Well.