Sunscreen does not interfere with vitamin D production

Controversy has flared up on social media again, this time over the use of sunscreen. The argument began when Tim Spector, professor of genetic epidemiology at King's College London, expressed concern that daily sunscreen use could lead to vitamin D deficiency.

While Spector's post caused a stir, it's not the first time similar arguments against sunscreen use have surfaced on social media—there are plenty of posts discussing the issue. Most of these concerns stem from the fact that sunscreen blocks the ultraviolet (UV) radiation needed for vitamin D synthesis in the skin. Fortunately, research shows that this is probably not a problem for most people.

Vitamin D is an essential nutrient. It helps regulate calcium absorption, which is important for bone health. A growing body of research also suggests that vitamin D may be important for other aspects of health, including boosting immunity, reducing inflammation and maintaining heart health. However, additional research is needed to confirm these findings.

Although we can get vitamin D from certain foods, such as fatty fish, egg yolks and fortified dairy products, our bodies primarily rely on sunlight to produce it in the skin.

When we are exposed to ultraviolet B (UVB) radiation, a series of processes occur in our skin cells that convert a cholesterol-like molecule into vitamin D3.

Since vitamin D production requires exposure to UVB radiation, it can be assumed that the use of sunscreen interferes with vitamin D synthesis.

Sunscreen acts as a filter, absorbing or reflecting the sun's UV radiation. The higher the sun protection factor (SPF) of a product, the better it protects against sunburn (mainly caused by UVB radiation). By preventing this radiation from reaching and mutating DNA in skin cells, sunscreens can reduce the risk of skin cancer. Sunscreens have also been shown to reduce UV radiation-induced skin aging.

However, sunscreens do not provide 100% protection - mainly because most people do not use them as intended. People typically only apply about a quarter to a third of the amount of sunscreen needed and rarely reapply as directed. This means that some UVB still reaches the surface of the skin.

Sunscreen and vitamin D

Many studies have examined the effects of sunscreen use on vitamin D levels. Overall, the results indicate that with typical use, sunscreen still produces adequate amounts of vitamin D.

In a study conducted by our research team, we conducted a week-long experiment with 40 holidaymakers in Tenerife, Spain. Participants were taught how to properly apply sunscreen with SPF 15 to protect their skin.

Sunscreen not only protected participants from sunburn, but also improved vitamin D levels. This showed that even when wearing sunscreen, enough UVB radiation still reaches the skin to allow vitamin D production.

These findings are consistent with two reviews that also looked at real-world sunscreen use and vitamin D levels.

Most of the studies included in these reviews either reported that sunscreen use had no effect on vitamin D levels or that sunscreen use resulted in increased vitamin D levels. This was especially true for field studies, which best reflected sunscreen use and sun exposure in real conditions.

However, these reviews also found several experimental studies (with more controlled conditions) that showed that sunscreen use may prevent vitamin D synthesis. However, these studies used UV sources not representative of solar UV radiation, which may limit their relevance to real-world conclusions.

Another limitation of the studies examined in these reviews was that most of them used low SPF sunscreens (around SPF 15 or lower). Public health recommendations suggest the use of sunscreen with an SPF of at least 30, which may potentially have a stronger inhibitory effect on vitamin D production.

And most of these studies included only white participants. White skin contains less melanin, which acts as a natural sunscreen, protecting against UV damage (including sunburn).

Melanin may also have a small inhibitory effect on vitamin D production. Observational studies consistently show that in people with dark skin, vitamin D levels usually lowerthan that of fair-skinned people living at the same latitudes. This difference becomes even more pronounced at higher latitudes, where UVB radiation levels are lower.

One review also found that people with fair skin types produce more vitamin D. However, this difference is likely due to differences in the methodology of the studies included in the review. Some have used artificial radiation sources, which do not represent solar UV radiation and may produce unrepresentative results.

More research is needed that includes people with darker skin types and using higher SPF sunscreens. But based on available evidence, typical sunscreen use does not interfere with the production of vitamin D. It also has the added benefit of preventing harmful UV rays.

Given that people with darker skin tones are at greater risk of vitamin D deficiency, spending more time in the sun may be beneficial. But although dark-skinned people have a 20-60 times lower risk of skin cancer than light-skinned people, it's still important to avoid the sun when it's at its strongest and Use sunscreen or cover your skin if you are outside on sunny days.