Vitamin D can be formed in the skin with the help of UV radiation.
Many believe that it is sufficient if you stay in the sun on a regular basis. But this condition alone is not enough to prevent a vitamin D deficiency.
Here are four common confounding factors that inhibit vitamin D production – even during summer.

Vitamin D needs sun

Vitamin D is actually not a real vitamin. After all, it does not have to be taken up with food - like other vitamins - but can be produced by the body itself. Vitamin D is therefore much more of a hormone than a vitamin. We only need sunlight (UVB radiation) that shines on our skin.

The UV-radiation is used to produce provitamin D3 from a substance (7-dehydrocholesterol), from which cholesterol can also be produced.

This then migrates with the bloodstream into the liver where it is converted to the actual vitamin D3, which then gets activated in the kidney.

Why do we need Vitamin D?

Vitamin D is responsible for many functions in the body. It boosts the immune system, prevents cancer and is an effective part of any treatment for diabetes, heart disease, hypertension, osteoporosis and Alzheimer's disease.

Furthermore vitamin D can also improve mood and relieve depression, help memory and improve the ability to find solutions.

A vitamin D deficiency is therefore often held responsible for the so-called winter depression, as it usually manifests itself in gloom and mental sluggishness.

In winter, the sun rarely shines - and if it does, only minimal amounts of the UV rays required for vitamin D formation reach the earth. But even during summer some experience a vitamin D deficiency. Here are the top four reasons you are not getting sufficient vitamin D and how to fix them.

1. Sun screen

Sun screens prevent sufficient amounts of the UVB radiation necessary for vitamin D formation from reaching the skin. Therefore the production of vitamin D is very little to not existent.

With a high sun protection factor, we give our body the feeling that it is permanently living in the middle of the gloomy winter.

2. Your latitude might sabotage vitamin D production

If you live north of the latitude of Barcelona (about 42nd latitude), you can only produce enough vitamin D in the summer months.

In the rest of the year, the UVB rays required do not reach the earth in the appropriate quantity due to the sun's angle of incidence, which is too flat. In the months November to February, they do not arrive at all on the earth's surface. And if you live north of the 52nd parallel, the latter period extends even further, from October to March.

3. Your skin colour can reduce the production of vitamin D

The brighter your skin colour, the faster you can produce vitamin D. 

Your skin type depends on which regions your ancestors lived in and how much sunlight they have been exposed to over the generations.

In the north, people therefore have lighter skin in order to be able to produce sufficient vitamin D as quickly as possible with the rare sun. In the south, however, the sun shines so often and so much that the skin has to protect itself from too much radiation, while vitamin D formation has never been a problem. Now it becomes problematic if a dark-skinned person lives in the north. The dark skin colour reduces the formation of vitamin D and an even longer stay in the sun is necessary in order to be able to produce sufficient vitamin D.

4. The UV-Index is too weak

The UV index indicates the radiation strength of the sun and should help to assess whether and which sun protection measures are necessary.

It goes from 0 to over 11. A value from 0 to 2 indicates a weak radiation intensity. A value from 3 to 5 is already stronger. Sun protection is already recommended here. For values above 8, it is not advisable to stay outdoors.

Time of year, day and the geographical location, but also cloudiness, air pollution and thickness of the ozone layer influence the UV index.

The UV index even depends on your environment. It is therefore crucial whether there is snow at the moment or whether you are lying on the beach. The brighter your surroundings (snow, sand), the more UV radiation can be reflected back onto you - sometimes up to forty times.

Only when the UV index is higher than 3 there are sufficient UVB rays present for vitamin D formation.

What can you do to always get enough Vitamin D?

We recommend to supplement with D3 during the winter months and depending on where you live also at other times. 

Here is how to calculate your requirements:

40-60 IU of vitamin D per kg of bodyweight.