Vitamin D

My “Smear it all over” campaign is aimed at raising awareness to parents and children of the importance of sun protection. Unprotected exposure to ultra violet rays (UVR) during childhood increases the risk of developing skin cancer in later life. But what about Vitamin D?


Healthy in the sun

As I have mentioned in a previous blog, DNA is more susceptible to DNA damage in children’s skin than in adults. Skin cancer rates have increased enormously in the last few decades and the age at which it is occurring is getting increasingly younger. This makes advice on how to protect your skin against the sun very important too. Information about sun protection also needs to include the positive side of sunlight. It is as though everyone is happier on sunny days, and furthermore sunlight causes the production of vitamin D which is important for our health. Vitamin D is essential for the healthy growth and development of our bones. Although “authorities” such as the IOM (Institute of Medicine), the AAD (American Academy of Dermatology) and the NGR (Nederlandse Gezondheidsraad) have stated recently that there is still insufficient proof, there definitely seems to be a link between vitamin D and conditions such as heart and cardiovascular diseases, diabetes, immunodeficiency disorders, infectious diseases, neurological conditions, muscular weakness, cramps and cancer. Time will tell!

What is Vitamin D?

Vitamin D is a fat soluble vitamin. There is a plant form (D2) and animal form (D3). We acquire Vitamin D through our diet (for example by eating oily fish and margarine) but the sun is a far more effective manufacturer of Vitamin D.
A short technical explanation: The influence of sunlight causes the conversion of the 7-Dehydrocholesterol, present in the skin, into Pro-Vitamin D3, which is then converted to Vitamin D3 (cholecalciferol). Vitamin D3 is subsequently transformed in the liver into the so-called 25-Hydroxyvitamin D-25 (OH)D (Calcidiol). Calcidiol acts as our internal supply of Vitamin D. Calcidiol circulates through the body and can be stored temporarily in the fat. The kidneys eventually form the active 1,25-Dihydroxyvitamin D (Calcitriol). So, quite a production process.

How can we make sure we get enough?

In order for the skin to start producing Vitamin D3, UVB rays are required (sun beds mainly use UVA). On the basis of research findings, we know that most children who are exposed to UVB for around 10 minutes a day in the Spring or Summer are able to make enough Vitamin D. So, outdoors every day then! In June when the sun is high in the sky, even short (2 to 5 minutes) exposure of the skin can result in maximum Vitamin D production. Having said that, long exposure to the sun is a waste of time for your Vitamin D creation. The maximum amount is created after a short time of exposure (around half of the time that it takes until your skin becomes light red), and thereafter the Vitamin D which has been created then breaks down again. It is another story in the Winter, when there is too little UVB light in the Netherlands for sufficient Vitamin D to be made from sunlight alone. We do have a supply of Vitamin D stored in our body, but it is even more important that, in the winter, we obtain Vitamin D from our diet and/or by taking food supplements. Be aware that we should eat a lot of oily fish, in particular, in order to gain enough Vitamin D from our diet.  Having just butter on our bread and an egg won’t actually be enough. This has been known for years; the well known cod liver oil was disgusting but did work well! Fortunately we’ve now got more pleasant alternatives… It is difficult to specify, beforehand, exactly how long it will take for you or your child to make Vitamin D. This also, in fact, depends on the exposed skin surface (if you wear short or long trousers), skin colour, rays strength (latitude and season), and the genes inherited from your parents. If you would like to know more then you can go to the Vitamin D calculator site.

Apply enough

With a view to the risk of skin cancer I wish to stress once again that there is no safe threshold for sun exposure. Research has found that your skin is already encountering damage, even before you burn. Protecting yourself properly is therefore important, but overdoing it is not smart either! Besides, life won’t be much fun if every couple of hours you are having to apply a thick layer of high factor sun cream all the year round… In view of the fact that in the finer months we can make Vitamin D rapidly in a short time, it is good to expose your hands and face to the sun for around ten to fifteen minutes. If you are staying in the sun longer then it is essential that you also protect your skin properly. I smear my kids in with a SPF 30 from April onwards before they go to school, and in warm weather I re-apply regularly. What is also important to know; numerous studies have found that normal use of a sun protection cream factor 30 doesn’t affect Vitamin D deficiency. Staying indoors a lot does affect it. So go outside and protect yourself well! The risk of sun damage is especially great between April and October so protecting is really a “must” then.

Just to round off!

We know that in the Netherlands many people suffer from a Vitamin D deficiency, and this is terrible because of the importance of Vitamin D to us. However, given the strong links between skin cancer and exposure to the sun, trying to build up Vitamin D by exposing your skin to sunlight for too long is unsafe. Prolonged, intensive sun exposure is ineffective because after a while your skin begins to break down the Vitamin D again. If you have darker skin, hardly go outside, you are younger than 4 years old, pregnant, breastfeeding, are a man over 70 years old or a woman over 50, then you should actually take a Vitamin D supplement all year round. If you don’t belong to the group at risk, but would rather be sure than unsure, then take a Vitamin D supplement during the Winter period. I do myself; better safe than sorry…

Some more sun, application and tips

1. Keep infants under 6 months out of the sun completely.
2. In the months from April to October confine outdoor activities without sun protection to the times when the UV index is below 3.
3. If the sun index is 3 or higher then protect the skin from the sun by use of a sun cream and/or clothing.
4. For daily protection on days when the UV index is 3 or higher, it is wise to smear schoolchildren in before school or protect the skin from the sun in another way. In sunny weather don’t forget to re-apply during the lunchtime or after school. You can also give your child a sun cream product to take to school. At the weekend it is fine if your children play outside for 10-15 minutes without protection in the morning or at the end of the day, during the midday a couple of minutes is usually enough for maximum Vitamin D production. Make sure in all cases  that the skin doesn’t become red!
5. With significant sun exposure (days with a high UV index, or a day at the beach) proper application is required according the guidelines. A thick layer of sun protection cream should be re-applied every two hours and after swimming. Protect the skin further through the use of clothing or UV resistant swimsuits.
6. There is a big chance of a Vitamin D deficiency in the Winter. Take note of the diet and possibly use a Vitamin D3 supplement. Supplementing is definitely required (also in the summer) if your child is under 4, or is at a higher risk because he/she is mostly indoors, has a darker skin colour, eats poorly or is overweight.
7. Use a SPF 30 on children, a factor less than 15 is never sensible. Recent advise from the Netherlands Association of Dermatology is to use a SPF 15 or SPF 30 daily and a SPF 30 for sun exposure in the holidays and free time. Higher protection factors than 30 are not usually necessary.

Regards and, above all, enjoy the lovely weather!


(Research Physician Cosmetic Dermatology)

You can also read the blogs:
Protect Yourself against the Sun; Apply Properly!’,
Self Confidence through the Sun (and Skin Cancer)’,
Skin Ageing Due to the Sun‘,
A Good Sun Cream?’,
and ‘
The Do’s and Don’ts of Safe Sun at a Glance’.