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Vitamin D and sunscreens: what we need to know

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Vitamin D and sunscreens: what you should know in Costa Rica

Dermatologists who treat skin cancer, moles, and dermatological oncologyVitamin D is essential for bone and muscle health, but its relationship with the sun often raises questions: Does using sunscreen prevent its production? Should we expose ourselves to the sun without protection? When is it advisable to take supplements? The answer isn't choosing between vitamin D and sun protection, but learning how to balance them.

Before reading: En skinpaths We distinguish between opinion and evidence. To write this content, we prioritized indexed medical sources and recommendations from scientific societies. At the end, you will find the complete bibliography for your reference.

Important: This article is for informational purposes only and does not replace medical advice. If you have any questions, persistent symptoms, or your condition worsens, consult a healthcare professional.

 

Summary in 60 seconds

  • Vitamin D helps the body absorb calcium and phosphorus, two minerals necessary for maintaining strong bones. It also plays a role in muscle, nerve, and immune function.
  • Vitamin D can be obtained from three main sources: sun exposure, food, and supplements. The skin produces vitamin D when it receives UVB radiation, but that same radiation can also cause sunburn, sunspots, premature aging, and skin cancer.
  • Sunscreens reduce the amount of UVB radiation reaching the skin. In laboratory studies, they can decrease the skin's production of vitamin D, but in real-world settings, evidence suggests that regular sunscreen use does not significantly reduce 25-hydroxyvitamin D levels in many people.

 

What is vitamin D and why is it important?

Vitamin D is a fat-soluble vitamin and a hormone precursor. Its best-known function is to promote the intestinal absorption of calcium and phosphorus. Therefore, it is important for bone mineralization and for preventing problems such as rickets in children or osteomalacia in adults. NIH 2025

It also plays a role in muscle function and immune processes. However, “more vitamin D” doesn’t always mean “better health.” Recent guidelines recommend avoiding routine vitamin D measurements in healthy adults without specific indications and not taking high doses without supervision. May 2024

What are the sources of vitamin D?

1. Sun exposure

  • The skin produces vitamin D when UVB radiation acts on a molecule called 7-dehydrocholesterol. The liver and kidneys then transform this vitamin D into forms usable by the body.NIH 2025).
  • This amount of sun exposure depends on many factors: time of day, season, latitude, cloud cover, pollution, skin color, age, clothing, time spent outdoors, and use of sun protection. Therefore, there is no single amount of sun exposure that is suitable for everyone.

2. Food

  • Few foods naturally contain vitamin D. Among the most relevant sources are fatty fish such as salmon, trout, tuna, and mackerel; fish liver oil; egg yolk; liver; cheese; mushrooms exposed to ultraviolet light; and fortified foods, depending on local availability. NIH 2022

3. Supplements

  • Supplements can be helpful when there is a confirmed deficiency or risk factors: limited sun exposure, advanced age, restrictive diets, intestinal malabsorption, bariatric surgery, kidney or liver disease, pregnancy, breastfeeding, or use of certain medications. Self-medicating with high doses is not advisable, as excess vitamin D can cause hypercalcemia and kidney or cardiovascular complications. NIH 2025

 

What are the symptoms of deficiency?

Vitamin D deficiency can be silent. When it does produce symptoms, these can include bone pain, muscle weakness, cramps, persistent unexplained fatigue, frequent falls in older adults, or fragility fractures.

In children, a severe deficiency can cause rickets. In adults, it can cause osteomalacia, a disorder of bone mineralization associated with bone pain and muscle weakness.NIH 2025).

These symptoms are not exclusive to vitamin D deficiency. Therefore, if they persist, it is not appropriate to assume the diagnosis, but to consult a doctor.

Why does responsible sun exposure help maintain adequate levels?

Because daily, moderate exposure to sunlight can contribute to vitamin D production. But “I need sun” doesn’t mean “I must get sunburned” or “I must get a tan.”

Responsible sun exposure means going outdoors regularly, avoiding sunburn, adapting exposure to skin type and UV index, and using protective measures when radiation is intense or exposure is prolonged.

NICE summarizes this balance by noting that communication about sun exposure should consider both the risk of skin cancer and the risk of vitamin D deficiency. NICE 2016

The key point is that using sunscreen does not equate to blocking all vitamin D production. The review by Neale et al. concluded that there is little evidence that actual sunscreen use significantly reduces 25-hydroxyvitamin D levels. Neale 2019

Specific measures (adequate vitamin D levels without neglecting sun protection)

1. Check the UV index

  • When the UV index is 3 or higher, sun protection is recommended, especially if you'll be spending time outdoors. Cancer Council Australia recommends sun protection when the UV index is 3 or higher, or when you'll be exposed to prolonged sunlight. Cancer Council Australia 2026

2. Choose a suitable sunscreen

  • Look for a broad-spectrum sunscreen with SPF 30 or higher, and make sure it's water-resistant if you'll be sweating or swimming. Apply it liberally and reapply every two hours if you're still outdoors, or more frequently if you're swimming, sweating, or toweling off. AAD 2025

3. Don't use sunscreen as permission to expose yourself more.

  • Sunscreen reduces the risk, but it doesn't make prolonged exposure harmless. Shade, hats, sunglasses, protective clothing, and avoiding peak sun hours are still essential.

4. Take care of your diet

  • Include dietary sources of vitamin D whenever possible: fatty fish, eggs, UV-exposed mushrooms, and fortified foods. This is especially important for people with limited sun exposure.

5. Consult before supplementing

  • Supplementation can be helpful, but it should be individualized. The Endocrine Society guidelines recommend against indiscriminate testing or supplementation in healthy adults without clear indications. May 2024

FAQ

Does sunscreen completely block vitamin D?

  • No. It can reduce the UVB radiation that reaches the skin, but it does not block 100% under real-world usage conditions.

Should I stop using sunscreen to increase my vitamin D?

  • No. If there is concern about a deficiency, it is safer to review diet, habits, risk factors, and possible guided supplementation.

How much sun do I need?

  • There is no universal figure. It depends on skin type, age, location, season, clothing, time of day, and UV index.

What foods contain vitamin D?

  • Fatty fish, fish liver oil, egg yolk, liver, cheese, UV-exposed mushrooms, and fortified foods.

Do I need to take a test?

  • Not always. It may be helpful in people with symptoms, risk factors, bone diseases, malabsorption, or use of certain medications.

Can vitamin D in supplements be dangerous?

  • Yes, if taken in excess. High doses must be prescribed and supervised.

What's better: sun, food, or supplements?

  • They don't compete with each other. For many people, the best strategy combines responsible outdoor living, proper nutrition, and sun protection.

 

Bibliography and sources

 

Content reviewed by:
Dr. Rodolfo Suárez
Medical Pathologist and Dermatologist
Master's Degree in Advanced Cutaneous Pathology
30/05/2026
19/06/2026
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