The sun and vitamin D

Dr. Jetske Ultee: “A lot of attention has in recent years been given to vitamin D. Or, more specifically, a lack of vitamin D, a problem affecting a large number of people all over the world. All of this attention is a good thing in my opinion, as vitamin D is very important for you; perhaps even more important than we realise. Vitamin D is necessary, for example, for healthy bones and also benefitting greatly from this vitamin is your skin. A deficiency is associated with various troubling disorders; from heart and circulatory problems and depression to immune disorders.

What does vitamin D have to do with skin care? Everything. We actually produce this vitamin in our skin through a reaction with sun light. And the question is whether all those sun creams are, in fact, such a good idea. Can your skin still make vitamin D if there is a thick layer of cream covering it?

The short answer is: yes. Various studies have also found that the use of sun creams is not the cause of the vitamin D deficiency in the world. There are other factors, however, which hinder the production of vitamin D, such as lack of sunlight, wearing clothes which cover your entire body (such as veiled women). It is also true that the thicker you apply sun cream the more inhibited vitamin D production will become. But this will not readily cause a deficiency.

I have made a summary below of studies in which you can read all about this. I found a very interesting study, by the way, into how in the future we could be using vitamin D as after sun. Make sure, as well, that you read the piece about the significance of the UV index. It explains clearly how this index signifies how and when to use your sun cream. And did you know that the sun creams with high UVA filters are also beneficial for vitamin D production? Finally, it isn’t a good idea to lie in the sun for longer in order to increase the production of vitamin D… So, are you going to read with me?”

“A sufficient intake of vitamin D through your diet is of course the best way, but that is sometimes very difficult in practise. I advise you, therefore, to take more of the vitamin orally. This is especially important for children, the elderly, people with darker skin and pregnant women.”

Does very little sun
automatically mean
too little vitamin D?

Although UV rays are necessary for the production of vitamin D, a shortage is still seen in areas where there is more than enough sunshine. And at the opposite end healthy vitamin D levels are found in people who have no exposure to the sun for months at a time. How exactly does this work and how can you maintain your level of vitamin D? All research hereafter is listed and discussed in this article overview.

Various reasons why people don’t get enough sunlight

There are various reasons indicating why people sometimes receive too light sunlight. That may be because of their daily work, for example underground or under water in a submarine. But populated areas and the climate you live in can also determine the amount of sun exposure during the year. Religion can also play a part because people cover up when they go out. The authors of this article collected 41 studies into the effect of these types of situation on the production of vitamin D.

What part does the season play on the vitamin D levels?

Most studies into the effect the seasons have on the vitamin D production look in particular at the difference in the winter and summer months. In almost all of these studies higher levels of vitamin D were found in the summer. More than half of the studies took place in countries or cities where an insufficient amount of UV radiation was received in order to be able to make vitamin D in winter. Unusually enough, this did not automatically lead to vitamin D deficiencies among the participants in the study. According to the authors a possible explanation for this lies in the vitamin D storage in the body. In the winter months the stored vitamin can be released. Another explanation could be that the dosage of UV radiation may have less of an impact on the vitamin D levels than thought. That theory is supported by another noticeable discovery: people in warm countries do not necessarily have a high level of vitamin D.

Do people who live close to the North or South Pole have a vitamin D deficiency?

Every year people residing close to the North or South Pole have to deal with a long period without much sunlight. This group is therefore interesting to study. From the available studies on residents in these places it appears that a quarter of them still had enough vitamin D in the body in the winter period. For some of them the explanation lay in their diet which was rich in vitamin D.

Does wearing long clothes cause a vitamin D deficiency?

It seems apparent that clothing which covers most of your skin obstructs the production of vitamin D. A vitamin D deficiency was found in veiled women in almost all of the studies carried out on vitamin D levels.

Can you have a vitamin D deficiency because of where you work?

The place in which you work can affect the amount of sunlight you are exposed to and, along with that, the amount of vitamin D in your body. Various available studies have shown that, in general, mine workers, factory workers and submarine crews have a shortage of vitamin D in their body.

It is better to get extra vitamin D through your diet than more sun

Based on all the research material, the authors of this overview article conclude that sunlight increases the vitamin D level in the body. But also that the vitamin D content can be sufficient in periods when there is no UV radiation. It is, according to them, concerning that vitamin D levels in many people are often too low in the summer too. Basically, more sunlight doesn’t seem to be the answer to this problem. In fact, vitamin D deficiencies also occurs in countries with sufficient amounts of sun. According to researchers it is better to ensure extra vitamins through a healthy diet.

Title: Limited exposure to ambient ultraviolet radiation and 25-hydroxyvitamin D levels: a systematic review

Year:  2015

Authors: S.A. Rice, M. Carpenter, A. Fityan, L.M. Vearncombe, M. Ardern-Jones, A.A. Jackson, C. Cooper, J. Baird, E. Healy


What if you work in
an office?

Even in sunny countries such as Australia vitamin D deficiency occurs. Office workers, for example, have been shown to be more at risk. This group doesn’t get much sun, an important source of vitamin D.

In this study Australian scientists researched the change in vitamin D levels, from season to season, in people who spent a large amount of time indoors. They also wanted to know if a change in exposure to the sun, diet, sport and outdoor activities and skin type within this group would have an effect.

Vitamin D at the end of winter and summer

The vitamin D status in the blood of 103 people with an office job in Sydney was measured at the end of the summer (end of March in Australia). At the end of the winter (late August there) 71 of them were re-checked.

Many people face a vitamin D deficiency

Approximately 30% of the participants were seen to have a shortage of vitamin D at the end of the summer. After the winter that was around 40%. It is a problem which appears, in particular, to affect people with a darker skin type. These results were nevertheless unusual, because approximately the same percentages of deficiencies were found for the whole population of Australia.

The researchers calculated that not only skin type played a part in the production of vitamin D, but also the time those participants spent in the sun, the amount of uncovered skin and the consumption of oily fish. A high concentration of vitamin D in the blood at the end of the summer appeared to coincide with a high concentration of vitamin D in the winter. Remarkably enough the use of sun cream actually seemed to coincided with a higher percentage of vitamin D. According to the researchers an explanation for this was that this group also spent more time in the sun.

Eat more fish and go outside more

Vitamin D deficiencies also occur in sunny places like Australia. And not only in office workers. Foods rich in vitamin D, such as oily fish and alongside that sports (outdoor) are, according to the researchers, advised in order to have enough vitamin D in the body.

It is better to have supplements for a deficiency than sun

This recent article by German specialists also underlines that more sun is not the answer for a vitamin D deficiency. More sun exposure causes an increased risk of skin damage such as skin cancer. Unfortunately the benefits of an increased production of vitamin D don’t outweigh this risk. The addition of the vitamin via diet and supplements is therefore preferable.

Title: Determinants of vitamin D status of healthy office workers in Sydney, Australia

Year:  2019

Authors: Fayet-Moore F, Brock KE, Wright J, Ridges L, Small P, Seibel MJ, Conigrave AD, Mason RS.


Title: Vitamin D and UV protection

Year:  2017

Authors: Stege H, Schwarz T.


A vitamin D
deficiency through
sun cream use?

In the past few years vitamin D deficiency has received a lot of attention. A worldwide problem that is associated with various chronic conditions. Vitamin D is produced in the skin under the influence of the sun’s rays. And because sun creams block out these rays the question is whether a lack of vitamin D can perhaps be as a result of the increasing use of sun cream products.

Measuring vitamin D in the blood

This study carried out in Rio de Janeiro in the winter examined the vitamin D levels of 95 healthy volunteers after exposure to the sun. One group used a sun cream product with SPF 30, another group used nothing and there was a control group that were not exposed to the sun. The vitamin D content in the blood plasma of all the volunteers was measured at the beginning and after 24 hours.

No less vitamin D if you apply sun cream

The researchers found no difference in the vitamin D levels of the group with sun cream and the group without sun cream on their skin who were exposed to the sun. The use of sun cream did not reduce the vitamin D production in the skin. But the researchers did find a significant difference in the group that didn’t go in the sun and the group that had applied sun cream on the skin. A lower vitamin D level was measured in the group that was not exposed to the sun.

Vitamin D deficiency and a change in lifestyle

Although the researchers stress that it is only a small study, they conclude that normal sun cream use doesn’t seem to stand in the way of vitamin D production in the skin. According to them the vitamin D deficiency ‘epidemic’ in the world cannot be attributed to the use of sun cream. Perhaps a change in our diet and lifestyle should be investigated more closely for the answer to an increase in the number of people with a vitamin D deficiency. Alongside this they list the arrival of indoor shopping centres, air-conditioned rooms and car use. These are factors which contribute to us having less UV radiation exposure.

Title: Evaluation of vitamin D plasma levels after mild exposure to the sun with photoprotection

Year:  2019

Authors: Luiza Alonso Pereira, Flávio Barbosa Luz, Clívia Maria Moraes de Oliveira Carneiro, Ana Lucia Rampazzo Xavier, Salim Kanaan, and Hélio Amante Miot


Does sun cream prevent
the production of
vitamin D?

The use of sun creams protects your skin from damage and skin ageing. But what effect does that sun protection actually have on the production of vitamin D in your skin? In this article the authors review all the scientific research that has been carried out into this.

Adverse effects on vitamin D production from sun filters

The authors ascertain that there is no known major study which shows that the use of sun cream prevents the production of vitamin D. The scientists did find three more minor studies which found that sun filters can be detrimental to vitamin D formation. Two of the studies involved experiments which took place inside. The subjects were exposed to UV radiation in a laboratory environment. Although the results of these studies are useful, they cannot be regarded in a practical sense. One of these studies is described in this article (link to the next article).

The third study, which depicted sun creams as having a negative effect, was conducted on former skin cancer patients. This group protected themselves with a sun cream product and was compared with healthy volunteers who didn’t apply sun protection. In this study the use of sun cream filters seemed to cause a decrease in vitamin D content. The authors actually remark on this finding. Because it is highly likely that the former patients avoided the sun more than the healthy people from the control group.

Does sun cream give you more time in the sun?

The authors also found studies where no effects from sun cream were measured against the production of vitamin D. In two of them volunteers who used sun filters were even found to have a higher level of vitamin D than participants who hadn’t applied any sun cream. An explanation for this could be that sun creams are often used by people who sunbathe a lot in order to get a tan.

Another study that was included in the article showed a strong connection between lower vitamin D levels and staying out of the sun, not going outside or the wearing of protective clothing.

Sun filters can block vitamin D production, however…

The authors conclude that sun filters can block the production of vitamin D in the skin. They also add, though, that it has never been proven with normal use in real circumstances (meaning outside of the laboratory).

They suggest that in everyday life people use less sun cream than the amount according to the guidelines of 2 mg per square cm of skin applied in the experiments. This would, according to the researchers allow for enough vitamin D to be made in the skin. They also think that people who use sun filters are in the sun more often than people who never apply sun cream.

Recent research

A new study was published recently in the British Journal of Dermatology wherein the same conclusion could be reached. Sun creams used daily do not stand in the way of vitamin D production. Even when they are used and applied optimally.

Title: Does chronic sunscreen use reduce vitamin D production to insufficient levels?

Year:  2009

Authors: M. Norval, H.C. Wulf


Title: Sunscreen photoprotection and vitamin D status

Year:  2019

Authors: T. Passeron R. Bouillon V. Callender T. Cestari T. Diepgen A.C. Green J. van der Pols B.A. Bernard F. Ly F. Bernerd L. Marrot M. Nielsen M. Verschoore N.G. Jablonski A.R. Young


Does applying a thicker
layer mean less
vitamin D production?

In order to protect your skin against the sun’s rays it is important that you apply a generous amount of sun cream. But can vitamin D then still be made in the skin? What effect does the thickness of the layer of sun cream you apply actually have? Does applying a thicker layer mean less vitamin D production?

Thick layer, thin layer

The participants were divided into four groups of seven for this experiment. One group applied a thick layer of sun cream, according to the guidelines of the World Health Organisation (WHO), of 2 milligrams per cm² of skin. The second group used ¾ of the amount, 1.5 mg per ²cm of skin. The third and fourth groups applied slightly less, ½ (1.0mg per ²cm) and ¼ (0.5mg per ²cm) of the amount respectively. Lastly there was also a control group that did not apply sun cream.

All the participants were exposed thereafter to a fixed amount of UVB radiation for twenty minutes. This procedure was repeated four times with 3 to 4 day intervals. I

Prior to and three days after the experiment the vitamin D level in the participants blood was measured.

Vitamin D production is dependent on the thickness of the sun cream

The researchers did indeed find an obvious link between the level of vitamin D and the thickness of the layer of sun cream applied. With each reduction in the amount of cream the vitamin D levels rose exponentially. When sun cream was applied according to the guidelines the vitamin D uptake, under the influence of the UVB light, was four times lower than when no sun cream was applied.

Title: The relation between sunscreen layer thickness and vitamin D production after ultraviolet B exposure: a randomized clinical trial

Year:  2012

Authors: A. Faurschou, D.M. Beyer, A. Schmedes, M.K. Bogh, P.A. Philipsen and H.C. Wulf


The effect of UVA filters
on the production of
vitamin D

The sun generates different radiation, including UVA and UVB. The latter is essential for the production of vitamin D in the skin. Sun creams are meant to deflect these rays. What effect does that have on the production of vitamin D in the skin? It has, in the meantime, been demonstrated in various studies that normal use of a sun cream doesn’t have to disrupt the production of vitamin D. Similarly here in this study. These researchers also looked at the effect of different sun creams with an SPF 15 containing both a high and low protection factor against UVA (UVA-PF).

Various products and application routines

The study took place on the island of Tenerife and comprised of three groups of Polish participants who were there on holiday for a week. The first group of 20 people received a sun cream product with an SPF 15 and a low UVA factor to use. The product had to be used following the instructions from the researchers. They stuck to the guidelines of a minimum of 2 mg of cream per ²cm of skin and re-applied regularly. For this, the participants received three tubes of 50 mg a day (in the morning, at midday and in the afternoon). The second group of 20 people applied sun cream following the same instructions with a product which also contained SPF 15 but with a higher UVA ray protection grade.

The third group of 22 people were allowed to apply sun cream when they felt it necessary and furthermore could use their own product. This group, as expected, applied less often and more liberally, the same way most people use sun cream. Lastly the control group comprised of 17 people who stayed at home in Poland.

More vitamin D readings

During the study the vitamin D level in the blood was checked. Both before and after the holiday. The blood samples were also analysed by two different laboratories using different techniques.

As demonstrated in previous studies these scientists found that the use of sun cream does not affect the production of vitamin D. A rise in vitamin D levels was measured in all 3 groups who used sun cream on the island for a week. The highest vitamin D levels were found in the ‘normal’ sun cream users group (those who didn’t follow the strict application guidelines). A decline in the blood was only observed in the people who stayed at home in Poland.

A higher UVA-PF, more vitamin D

An interesting finding was that more vitamin D was seen to be produced in the skin of the group with the high UVA-PF than the group with the cream with the low UVA protection factor. Why? Products which block out more UVA let more UVB in. And more UVB means more vitamin D production.

Higher UVA-PF, more protection for skin…

The different effects of sun cream with a high and low UVA protection grade (but with the same SPF above 50), after exposure to UV radiation, was already looked at in countless laboratory settings. In these experiments products with a higher UVA-PF came out on top, they offered more protection against damage to the epidermis and dermis.

According to the researchers, in this study (in addition realistic circumstances) it is the first time that a higher UVA protection is also seen to be advantageous for the synthesis of vitamin D. They think that sun protection with a high UVA-PF is preferable anyway because there is increasing evidence that UVA (in particular UVA1, 340-400nm) is more damaging to skin than thought. During formation the skin layer with melanocytes and keratinocytes is sensitive to these rays.

A balance between the benefits and drawbacks of the sun

The authors conclude that sun creams should be designed in such a way that there is a good balance between the benefits and drawbacks of sunshine on the skin. They have demonstrated that it can in this study.

Title: Optimal sunscreen use, during a sun -holiday with a very high UV index, allows vitamin D synthesis without sunburn

Year: Mei 2019

Authors: A.R. Young 1, J. Narbutt 2 * , G.I. Harrison 1, K.P. Lawrence 1, M. Bell 3, C. O’Connor 3, P. Olson 4, K. Grys 1, K. Baczynska 5, M. Rogowski -Tylman 6, H.C. Wulf4, A. Lesiak 2, P.A. Philipsen 4

British Journal of Dermatology


Use sun cream when UV
index reaches 3 so that we
produce enough vitamin D?

The dilemma has already been mentioned here. Sunshine is the most important source for the production of vitamin D. At the same time exposure to the sun means the skin is at risk. Therefore, advising people about safe sun use is tricky. The sun shine is not the same each day, everyone is unique and furthermore where you live makes a big difference. When is it best to apply sun cream and when is it best, for vitamin D production, not to?

According to the World Health Organisation (WHO) the current guideline is to start applying sun cream when the UV index reaches 3. What is that based on precisely? Are the current recommendations correct? Australian scientists answer that question in this article.

What is the UV index?

The UV index, also referred to as solar power, gives us an indication of the intensity of the sun’s rays. This is not determined as you may think by the temperature of the sun, but by the position of the sun. As the sun gets higher the UV intensity increases. So the index varies according to the seasons and also to the time of day. The amount of UV radiation is also affected by clouds, humidity or particles in the atmosphere and how thick the ozone layer is. Therefore the UV index can still be higher on a cool day than on a warm day.

What does the UV index say about sun cream application?

The solar power determines how long skin can be exposed to UV rays without burning. But your skin type is important if you want to know how long that actually is. Alongside this, the conditions and situation in which a person finds themselves play a part (is there shade, is someone sunbathing or just walking in the sun).

Deciding whether to apply sun cream should not only be based on the UV index. The length of time you spend in the sun is just as important. If the index, for instance, is 6 then someone can burn after 20 minutes. And if the UV index is 2 then you would burn after 60 minutes.

This is because while the quantity of UVB may be low with low solar power, you can still receive a high dose of UVA on the skin. And what we do now know is that UVA is also harmful to skin.

The UV index doesn’t necessarily speak for the UVA quantity

The relationship between the UV index and UVB is linear. That means that the higher the solar power is the more UVB there is. The quantity of UVA, however, can vary considerably in a given amount of solar power. That can relate to the amount of ozone in the air, the cloud coverage and the position (angle) of the sun. One day with UV index 3 is therefore not the same as another day if the amount of UVA radiation is taken into consideration, the same goes for the location.

UV index and the production of vitamin D

So how is vitamin D production affected? One important reason why it is often advised not protecting yourself in the sun if the UV index is lower than 3 is so that enough vitamin D can be produced. The researchers make a fine distinction about this. If the solar power is low it means that the quantity of UVB is low. In order to produce enough vitamins in the skin you need to spend some time in the sun, and that can still cause damage. This applies in particular to darker skin. It is harder for this skin type to make vitamin D. And even more so if the skin is mostly covered. In the article the Australian scientists provide some examples with different UV indexes. Therefore, according to them, the advice not to use sun cream below UV index 3 is too black and white.

Time for a new UV index?

The authors are of the opinion that it is a good idea to refine the UV index further and adapt it better to more extreme weather conditions which occur outside Europe. At the moment the scale for solar power goes up to 11+ but double that amount can be reached in some parts of the world. The time spent in the sun also needs to be included in the current advice for applying sun cream. If the solar power increases then you need to spend less time in the sun or apply more and more often or do both.

The researchers once again highlight the importance of the daily use of a sun cream. This can really reduce the instances of skin cancer. At the moment sun cream is often just used for preventing sun burn. They do acknowledge that their findings and advice are based on a sun drenched part of the world (Australia) and that this may not necessarily apply to all parts of the world.

Title: Are current guidelines for sun protection optimal for health? Exploring the evidence

Year: 2018

Authors: Lucas RM, Neale RE , Madronich S , McKenzie RL.


Vitamin D as an
after sun?

A high dose of vitamin D taken orally after burning in the sun can limit redness, inflammation and skin damage. This was found in an American study. Vitamin D as an after sun would be perfect. But how exactly does it work?

Worldwide attention has been given to the consequences of vitamin D deficiency and the use of supplements. A deficiency in the vitamin has been linked to several conditions, including heart and vascular diseases, (winter) depression, diabetes, neurological conditions such as M.S. and even cancer. It is becoming more and more obvious that vitamin D plays an important role in our bodies in the course of inflammatory reactions and our immune response.

So, can extra vitamin D in tablet form also halt inflammatory processes? A pilot study into the effect of vitamin D on sunburnt skin was set up in order to test this theory. (A pilot study can be seen as preliminary research)

The effects of a high dosage of vitamin D3

In this study a small group of 20 participants was investigated. The skin on the inside of their arms received radiation from a UV lamp. An hour after this simulated sun burning a high one off dosage of 50.000, 100.000 or 200.000 IU (IU stands for International Unit) of vitamin D3, or a placebo pill, was randomly administered to the test subjects. Thereafter the participants were monitored at set times of 24 hours, 48 hours, 72 hours and a week after the experiment. Redness, swelling and inflammation in the skin was also investigated. Blood samples were also taken.

Inflammatory response significantly reduced through vitamin D

The results of the study showed that taking vitamin D orally can significantly reduce the inflammatory response in the skin. The effect was also dosage dependent. The people who received the highest dosage of vitamin D looked as though their skin benefitted the most. They were suffering much less of an inflammatory response after 48 hours. Their skin was also less red than the skin of the people in the placebo group.

Also measured in the people with a high dosage of vitamin D was an increased activity in the genes involved in repairing the skin’s barrier.

Tablets for prevention or after sun burn?

Based on this pilot study the researchers are unable to give any recommendations about the (extra) use of vitamin D. Much more research is necessary for this, moreover, with larger groups of participants.

The conversion and storage of vitamin D in the body are complex processes. The difficulty, for instance, is deciding what dosage is required depending on the vitamin D content already present in the body.

Another question would then be if you could prevent sun burn with extra vitamin D? And how much should you then take?

Extra vitamin D for groups at risk

At the moment extra vitamin D intake is recommended for specific risk groups such as people with darker skin, the elderly and babies who do not produce enough vitamin D themselves. The doses of vitamin D that have been researched in this exploratory study are significantly higher than the amount which would be advised for daily use (400 to 800 IU or 10 to 20 micrograms).

Follow up study

A study has since been published confirming the idea that vitamin D could act as a “treatment” for skin damage, such as burning. In this complex article the effect of the vitamin on certain parts of the immune system has been discussed in detail.

It is in fact a fine mechanism. Vitamin D is produced in the skin, under the influence of UV radiation. But too much UV radiation will then cause damage. The skin therefore has all kinds of smart tricks to protect itself against this. It appears that vitamin D has an important task in clearing up this damage.

Title: Oral vitamin D rapidly attenuates inflammation from sunburn: an interventional study

Year: 2017

Authors: Jeffrey F. Scott , Lopa M. Das , Sayeeda Ahsanuddin , Yuqi Qiu , Amy M. Binko , Zachary P. Traylor , Sara M. Debanne , Kevin D. Cooper, Rebecca Boxer , and Kurt Q. Lu


And in this article you can read an explanation about the study: Link

Title: Vitamin D improves sunburns by increasing autophagy in M2 macrophages

Year: 2019

Authors: Lopa M. Das , Amy M. Binko, Zachary P. Traylor, Han Peng & Kurt Q. Lu