It all starts again on social media. This time we will talk about how to apply sunscreen. The debate began after Tim Spector, professor of genetic epidemiology at King’s College London, raised concerns that daily sunscreen use could lead to vitamin D deficiency.
Although Spector’s post received a lot of attention, it wasn’t the first time the argument against using sunscreen has taken to social media, and there have been countless posts discussing the issue. Most of these concerns stem from the fact that sunscreens block ultraviolet (UV) radiation, which our bodies need to synthesize vitamin D in the skin. Fortunately, research shows that this is probably not a problem for most people.
Vitamin D is an essential nutrient. Helps regulate calcium absorption, which is important for bone health. A growing body of research suggests that vitamin D may also be important in other aspects of health, such as boosting immunity, reducing inflammation, and maintaining heart health. However, further studies are needed to confirm these findings.
Although vitamin D can be obtained from certain foods such as oily fish, egg yolks, and fortified dairy products, our bodies primarily use sunlight to produce vitamin D in our skin.
When we are exposed to the sun’s ultraviolet B (UVB) rays, a series of processes within our skin cells convert cholesterol-like molecules to vitamin D3.
Since the production of vitamin D requires exposure to UVB radiation, the use of sunscreens would be expected to inhibit vitamin D synthesis.
Sunscreen acts as a filter, absorbing or reflecting the sun’s ultraviolet rays. The higher the sun protection factor (SPF) of a product, the more effective it is at preventing sunburn (mainly caused by UVB radiation). Sunscreen can reduce your risk of skin cancer by preventing this radiation from reaching your skin cells and mutating your DNA. Sunscreens have also been shown to reduce skin aging caused by UV rays.
However, sunscreens are not 100% effective. This is mainly because most people don’t use it as directed. Typically, people only apply one-quarter to one-third of the amount of sunscreen they need and most people don’t reapply as directed. This means that some UVB can still reach the surface of your skin.
sunscreen and vitamin D
Many studies have investigated the effects of sunscreen use on vitamin D levels. Overall, research shows that sunscreen allows for sufficient vitamin D production even with regular use.
In a study conducted by our research team, we conducted a week-long experiment with 40 vacationers on the Spanish island of Tenerife. Participants were instructed on how to properly apply SPF 15 sunscreen to protect their skin.
Not only did the sunscreen protect participants from sunburn, but it also increased their vitamin D levels. This showed that even when using sunscreen, enough UVB radiation reaches the skin to produce vitamin D.
These findings are consistent with two reviews that also looked at actual 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 led to increased vitamin D levels. This is especially true for field studies, which are likely to best reflect real-world sunscreen use and sun exposure.
However, these reviews also found some experimental studies (with more controlled conditions) showing that sunscreen use can interfere with vitamin D synthesis. However, these studies use UV sources that are not representative of solar UV radiation, which may limit their relevance to real-world conclusions.
Another limitation of the studies evaluated in these reviews is that most studies used low SPF sunscreens (approximately SPF 15 or less). Public health recommendations recommend the use of sunscreens with at least SPF 30, which may have a greater inhibitory effect on vitamin D production.
And most of these studies only included white participants. White skin has less melanin, which acts as a natural sunscreen and protects against UV damage (including sunburn).
Melanin may also have a potentially small inhibitory effect on vitamin D production. Observational studies have consistently shown that people with darker skin tend to have lower vitamin D levels than people with lighter skin living at the same latitude. This difference is even more pronounced at higher latitudes, where levels of UVB radiation are lower.
One review also found that people with lighter skin produce more vitamin D. However, this discrepancy is likely due to differences in how the studies included in the review were conducted. Some use artificial radiation sources, but these do not represent the sun’s ultraviolet radiation and may yield non-representative results.
It is clear that further research needs to be conducted in people with darker skin and those who use sunscreens with high SPF. However, based on the evidence we have, common sunscreen use does not inhibit vitamin D production. It also has the effect of preventing damage from UV rays.
Given that dark-skinned people are at higher risk of having low vitamin D levels, spending more time in the sun may be beneficial. However, although dark-skinned people have a 20 to 60 times lower risk of skin cancer than lighter-skinned people, they should still avoid when the sun is at its strongest and avoid being outdoors on sunny days. It is important to wear sunscreen or cover your skin.
This article was originally published in The Conversation by Karl Lawrence and Antony Young, King’s College London. Read the original article here.
