The sun is great! It gives us warmth, gives us light during the day and can now even charge our mobile phone batteries using solar cells. But it’s not just electrical appliances that can tap energy from ubiquitous sunlight: we do it too! For example, our body is able to independently generate vitamin D from the sun.
This ability to synthesize vitamin D is also great! After all, other essential nutrients often have to be absorbed through the diet. The image by the sun is therefore a clear exception and the process behind it is highly interesting.
Of course, the questions that arise from this are also particularly exciting:
- How much sun do you need to meet your vitamin D needs?
- Does clothing make a difference?
- What about sunscreen?
- Are there other factors to consider?
Here you will find answers to all these questions and tips on how to best get vitamin D from the sun.
The basics: How sunlight becomes vitamin D
Converting sunlight into vitamin D is actually nonsense. Strictly speaking, the light is not converted at all, but rather serves as a kind of activator.
A precursor of the vitamin is already produced in the liver from cholesterol. The UV radiation then stimulates the synthesis of vitamin D3, also cholecalciferol, from this vitamin D precursor in the epidermis.
Via the kidneys, vitamin D3 is then converted into its “activated form”, calcitriol, and can thus be used by the body as “vitamin D”.
UVB radiation in sunlight is crucial for activation, as only this particular part of the light triggers the synthesis of the vitamin. For this reason, you will not produce vitamin D even after hours in the solarium. In contrast to the real sun, artificial sunlight is mainly based on UVA radiation.
What is really important is the direct incidence of sunlight on the skin. Clothing and even glass filter out the required UVB radiation.
How long do you need to be in the sun to satisfy your vitamin D needs?
In general, the daily requirement of vitamin D is given as about 20 μg or 800 IU (International Units). To achieve this through synthesis in the body, it is usually enough to spend about 15 minutes in the sun (arms and head uncovered).
That sounds very little at first. However, this number should be treated with caution, because vitamin D synthesis is influenced by numerous factors. One of them is, for example, the time of day and season.
In Central Europe, for example, the UV radiation required for vitamin D is greatly reduced in the morning and evening hours as well as in winter. In particularly unfavorable weather conditions, vitamin D production is even completely suspended. Therefore, the synthesis only works effectively in the warmer months between 10 a.m. and 4 p.m. Stupidly, this is exactly the time when most working people have little chance of direct sunlight.
But skin color also determines how much vitamin D we produce.
What does the skin type have to do with it?
The 15 minutes of sun from above depend on an average, Central or Northern European skin type. This recommendation is primarily based on the
minimum erythema dose of
this particular skin color. Put simply, this is about half the time until the skin turns red due to the sun’s radiation, i.e. shows the first signs of sunburn.
Pale people or people with dark skin must therefore be in the sun for a shorter or longer period of time in order to produce the same amount of vitamin D:
|Skin||Time in the sun to meet vitamin D needs
(in summer, in Central Europe)
|pale skin, reddish hair||
|People from Northern Europe, blonde hair||
|Mixed type, darker hair||
|People from Southern Europe / Asia,
black / brown hair
|People from India / North Africa, black hair||
Does sunscreen reduce vitamin D from the sun?
Since the production of vitamin D happens through the skin, the question naturally arises as to what effect the application of sunscreen has on the synthesis of the vitamin.
In fact, less vitamin D is produced from a relatively low sun protection factor. However, in order to severely limit the synthesis of the vitamin, the sunscreen must be applied quite thickly, which usually does not happen.
With normal application, the skin should still be able to produce vitamin D, albeit to a lesser extent.
It’s all in the mix: How to refuel vitamin D properly
Some doctors and scientists face the conscious refueling of vitamin D by the sun with mixed feelings. On the one hand, sunbathing is an effective way to produce vitamin D, but on the other hand, solar radiation is always accompanied by a certain risk.
Especially in strong sunshine and direct radiation, you run the risk of developing a sunburn after a short time. This slight burn of the skin by ultraviolet radiation seems relatively harmless at first, as even severe sunburns usually heal after a few days. However, the fact that sunburns are a risk factor for the development of black skin cancer should not be ignored. Especially sunburns in childhood are suspected of being a decisive factor in the development of skin cancer later in life.
In addition to this risk, vitamin D synthesis by the sun is influenced by a whole host of factors such as weather, season and time of day or the clothing worn. All of this can make the effective production of vitamin D by sunlight a challenge.
Finally, here are the most important tips to recharge your batteries with vitamin D:
- Adjust your time in the sun according to your skin type. A sunburn should be avoided as much as possible, in case of doubt better to use the sunscreen!
- If you tend to develop a sunburn quickly, you can also go out in the sun in cloudy skies or in the morning or evening. The vitamin D production is lower, but you minimize your risk of sunburn.
- If you basically get little in the sun, a vitamin D deficiency could arise. However, this can be easily compensated for with vitamin D capsules or with a targeted diet containing vitamin D. If you suspect, medical advice will always help you here.