Vitamin D substitution - useful or just hype?

Taking vitamin D supplements has been discussed by scientists for years, and this topic comes up again and again, especially in the winter months. But how exactly can a vitamin D deficiency actually occur, why can it be dangerous and who can be affected by it? We would like to give you the most important information about vitamin D.

What exactly is vitamin D? 

Vitamin D is - contrary to the name - not a vitamin at all, but a pre-hormone, since it can only be formed in the skin with the help of UVB rays from a precursor (7-dehydrocholesterol). The human need for vitamin D can be covered by sunlight and food. However, absorption via light is much more effective, because vitamin D synthesized via the skin has a span in the blood that is twice as long as vitamin D absorbed via food or other supplements.

But what do we need vitamin D for anyway?

Vitamin D is essential for our body and is needed for many processes. It supports the immune system, strengthens the bones and helps the muscles. The pre-hormone promotes the absorption of calcium and phosphate from the intestine and their use in the bones. An extreme deficiency can therefore lead to damage to the bones, which can manifest itself in bone loss or bone deformation. Furthermore, vitamin D has an influence on the production of the messenger substances serotonin and dopamine in the brain, which among other things regulate activity, mood and mental state.

In addition, a deficiency makes one more susceptible to infections, as the immune system is weakened. A connection between vitamin D deficiency and diseases such as type 2 diabetes, cardiovascular diseases and even multiple sclerosis and cancer is also suspected. However, there are contradictory scientific findings on this so far. 

How can vitamin D deficiency develop?

There are certain factors that can favor the occurrence of a deficiency, including too little time outdoors or in sunlight, which is favored by our current lifestyle but also the geographical location in the northern latitudes. In the months from March to October, the sunlight is strong enough even in our country that 20-30 minutes of sunlight daily can lead to sufficient vitamin D formation. However, the altitude, the ozone content of the air and air pollution also play a role here. During the rest of the year, the radiation is usually not sufficient to cover the vitamin D requirement alone.

In addition, older people are more susceptible to a deficiency because the skin changes with age and is able to synthesize less. Overweight individuals may also be more likely to be affected due to greater absorption of vitamin D into fatty tissue. The color of the skin also plays a role; darker skin types are more likely to suffer from a deficiency because more UV exposure is needed. Furthermore, various chronic diseases such as renal insufficiency or the intake of certain medications play a role.

What are the typical symptoms of a vitamin D deficiency?

The functions that vitamin D performs in the body have already been explained. This can result in the following symptoms in the case of a deficiency:

From a psychological point of view, it often makes itself felt through mood swings, fatigue and difficulty concentrating. Physiological symptoms can be, among others, bone pain, respiratory infections or hair loss.

Please note: This article is not a substitute for advice from a medical professional. Symptoms can be very individual in both form and intensity. Certain symptoms may also be caused by other conditions. Please always consult your healthcare professional if you experience symptoms.

So rather substitute quickly?

Scientists have repeatedly criticized the use of vitamin D supplements. This is based on the one hand on the fact that vitamin D should not be seen as a "panacea", since some of the effects attributed to it have not yet been conclusively clarified scientifically. 

On the other hand, the critics are concerned that the vitamin should not simply be taken blindly and without medical consultation. An excessively high dose of vitamin D can also have harmful effects: it results in an elevated calcium level, which can lead to nausea, stomach problems and, in serious cases, kidney damage and cardiac arrhythmias.

The body is quite capable of storing vitamin D and, despite reduced possibilities, producing it to a certain extent even in winter. It can therefore not be assumed in principle that all people suffer from a vitamin D deficiency in the darker months. The body's ability to produce its own vitamin D may be reduced by the above-mentioned circumstances, among other things, but here, too, it is not possible to make a general assessment. To find out your individual needs, a blood test is indispensable. However, it should also be noted that this is a snapshot and even if the value is low, it cannot be assumed that you have a chronic vitamin D deficiency. Let your doctor advise you whether and to what extent a substitution is necessary and sensible for you.

So, as is often the case, medical consultation and plenty of exercise in the fresh air is useful to stay fit and healthy. Use the weekend or your lunch break, for example, to go for a long walk.

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Sources:

- Antworten des Robert Koch-Instituts auf häufig gestellte Fragen zu Vitamin D. Robert Koch Institut. Januar 2019.

- Hype um Vitamin-D-Substitution. Was bleibt? H. A. Bischoff-Ferrari. September 2020.

- Vitamin D-Produkte – Wann sind sie sinnvoll? Verbraucherzentrale. November 2020.

- Vitamin D Mangel. Medix. F. Huber, U. Beise. September 2016.

- Vitamin D. Ärzteblatt Sachsen. S. Karger, A. Roth. September 2017.

- Vitamin-D-Substitution. Pharmazeutische Zeitung. C. Müller. Juni 2019.