Does applying sunscreen cause vitamin D deficiency? Since we naturally produce vitamin D from sunlight, it's a reasonable question. But let's see what the science actually says, particularly for those of us with skin of colour.
What is Vitamin D and what is its role in our body?
Vitamin D has numerous functions in the body. It helps keep bones strong, the immune system working, and even heals and protects the skin. When our skin is exposed to UVB rays from the sun, specifically around the 297 nm wavelength, our bodies make vitamin D. This process starts in the skin and goes through a number of steps before calcitriol, the active form of vitamin D, is ready to do its job in the body.
Keratinocytes, which are skin cells, can make their own vitamin D and respond to it directly. This helps with repair, lowers inflammation, and even protects against some of the sun's harmful effects. This local vitamin D pathway could be one reason why phototherapy works for psoriasis and other skin conditions.
Melanin's Role in Vitamin D Production
Melanin is a key molecule in skin of colour individuals that changes the whole vitamin D dynamic.
Melanin is a natural UVB filter that also protects the skin from the sun. This makes it harder for the skin to start making vitamin D. The same molecule that protects against UV damage also stops the skin from making vitamin D from UVB by blocking some of the UVB from getting to the deeper layers of the skin.
This is especially important because people with deeper skin need to spend a lot more time in the sun to get the same amount of vitamin D as people with lighter skin. This natural difference in how UV light is processed is one of the main reasons why people with darker skin are more likely to be vitamin D deficient.
Skin of Colour and Vitamin D Synthesis
Research shows that the efficiency of vitamin D synthesis reduces as skin type advances from I to VI. For instance, it might take two hours of sun exposure for skin of colour to get the same effect as 30 minutes of exposure for lighter skin. This means that people with deeper skin are always at a higher risk of not getting enough vitamin D, even if they use sunscreen.
Do sunscreens really stop the body from making vitamin D?
People often think that sunscreens might make it harder for the skin to make vitamin D because they are made to block UVB and UVA rays. In theory, this is possible, especially in a controlled lab setting where sunscreen is applied to all exposed skin at the recommended thickness and reapplied often. But in real life, things are different.
In places like India, people usually only put sunscreen on their faces, which is only 4–5% of the body's surface. People don't always reapply, and when they do, it's often hindered by the heat, humidity, or worries about acne or how their skin feels. Because of this, large parts of the body are still exposed to UVB, even in people who use sunscreen all the time.
What studies say about Sunscreens and Vitamin D Levels?
Due to this limited and inconsistent application, the use of sunscreen in practical scenarios is unlikely to significantly lower vitamin D levels. Numerous studies have validated this, including Indian research involving women with melasma, which indicated no significant differences in vitamin D status between sunscreen users and non-users.
Interestingly, sunscreen use does not completely inhibit vitamin D synthesis, even in highly controlled environments. A 2019 study showed that people who used SPF 15 sunscreen in the right amounts during a week-long vacation with a high UV index still had a significant increase in their serum vitamin D levels. The group that used sunscreen with more UVA protection actually made more vitamin D because those types of sunscreen let more UVB through by design.
This supports an important point: sunscreens can protect against sunburn and photodamage while still allowing enough vitamin D to be made, especially when used in real life, where they are only partially applied and not reapplied often.
Why is Vitamin D supplementation essential for Skin of Colour?
For individuals with skin of colour, oral supplementation remains the most effective and reliable way to ensure adequate vitamin D levels, given the reduced efficiency of synthesis in skin due to higher melanin content.
Clinical guidelines now suggest aiming for a serum 25-hydroxyvitamin D level between 40 and 60 ng/ml for maximal benefit. Levels below 40 ng/mL may not fully support the broader systemic roles of vitamin D, such as immune modulation and cardiovascular protection, while levels above 60 ng/mL may carry a higher risk of adverse effects.
Vitamin D requirements during Pregnancy, Infancy, and Beyond
The change in requirements is especially important when a woman is pregnant or has a baby. Neonates born to moms with higher skin types frequently exhibit reduced cord blood vitamin D levels, indicating maternal insufficiency.
Children with deeper complexion also need more vitamin D to reach and maintain the right amounts in their blood. For example, light-skinned children may only need 240 IU/day to get enough vitamin D, but children with deeper skin tone may require 560 IU/day to get to 30 ng/ml and up to 28 mcg (1120 IU/day) to get to 50 ng/ml, which is the best amount.
Because of these differences, it is highly suggested that people with deeper complexion have regular screenings and supplements, especially during times when they are most vulnerable, like during pregnancy, infancy, and after menopause.
Why sunscreen use is still important for Skin of Colour?
The conversation around vitamin D should not undermine the importance of daily sun protection, especially for skin of colour, where conditions such as melasma, post-inflammatory hyperpigmentation, and cumulative photodamage are not only more prevalent but also more resistant to treatment. Regular sun protection remains a foundational part of managing these conditions.
Newer sunscreens, especially ones made with deeper skin in mind, do more than just protect against UVB rays. Protection now includes UVA and visible light spectrum, especially blue light, which is increasingly recognised as a contributor to pigmentation. The UVB wavelengths that help make vitamin D are not the same as the ones that cause skin pigmentation and aging. This distinction makes it possible to come up with smart formulation techniques that provide everyday protection where it matters and allow supplementing to meet systemic vitamin D demands.
A Quick Summary for You
Vitamin D deficiency is common in skin of colour due to higher melanin levels and reduced cutaneous synthesis.
Sunscreens, as used in daily life, do not cause significant reductions in vitamin D levels.
Supplementation is the most reliable and recommended strategy, especially in deeper skin tones.
Sun protection remains essential in preventing pigmentary and aging-related skin issues.
The conversation is not about choosing between sunscreen and vitamin D, but about understanding how both can, and should, coexist in good clinical care.
References
- Bikle DD. Vitamin D: Production, Metabolism, and Mechanism of Action.
- Brenner et al., The protective role of melanin against UV damage in human skin. Photochem Photobiol.
- Mostafa et al., Vitamin D and the skin: Focus on a complex relationship: A review. J Adv Res.
- Singh et al., Does using a high sun protection factor sunscreen on face, along with physical photoprotection advice, in patients with melasma, change serum vitamin D concentration in Indian conditions? Indian J Dermatol Venereol Leprol.
- Young et al., Optimal sunscreen use, during a sun holiday with a very high ultraviolet index, allows vitamin D synthesis without sunburn. Br J Dermatol.
- Chauhan et al., Vitamin D. In: StatPearls