Vitamin D: Immunity boosting Covid-19 protection?

Vitamin D is one of the most important vitamins that are necessary for the healthy functioning of the human body. Not only does it ensure the proper functioning of the muscles, bones, and joints but also plays a key role in developing the immune system. People with vitamin D deficiency are more likely to get seriously ill when they become infected with Sars-CoV-2, but this does not mean that taking vitamin supplements protects people without vitamin deficiency from severe disease.

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Vitamin D is crucial for the immune system

Researchers led by Prof. Hans-Konrad Biesalski at the University of Hohenheim have evaluated 30 studies that shed light on the relationship between vitamin D and the impact of Covid-19 infections. In other words, the vitamin D supply of a Covid 19 patient could possibly directly influence the severity of the disease.

Above all, vitamin D has a decisive influence on bone metabolism, but it also plays a major role in other processes in the body – for example in defence reactions of the immune system. For example, the vitamin is important for the work of various immune cells. It has an antimicrobial effect against bacteria, fungi and enveloped viruses such as coronaviruses. In addition, vitamin D inhibits the production of inflammatory messenger substances and increases the production of anti-inflammatory cytokines.

Excessive inflammatory reactions from Covid-19

Inflammatory processes that have gotten out of control are a central complication in Sars-CoV-2 infections. “The result is serious changes in the alveoli, which lead to a serious complication of Covid-19 disease, the so-called acute respiratory distress syndrome,” said study leader Biesalski.

In some cases, the immune system overreacts to the coronavirus infection, releasing massive amounts of cytokines that promote inflammation. This so-called cytokine storm affects the whole body in a life-threatening way – similar to what happens with blood poisoning (sepsis). A lack of vitamin D could therefore increase the risk of such unchecked immune reactions.

Vitamin D is not a medication to cure Covid-19

In order to avoid misunderstandings, the doctor emphasizes: “Vitamin D is not a drug that can be used to cure Covid-19 infections. It can however have a positive effect on the course of the disease by enabling the organism to restore the balance between the pro and anti-inflammatory processes. ”

Although researchers have found that people with a vitamin D deficiency are more likely to get seriously ill from the coronavirus, it is still unclear that deficiency is solely responsible for this. Rather, vitamin D levels often reflects a patient’s state of health. Vitamin D deficiency and previous illnesses often occur together.

In any case, low vitamin D levels occur more frequently in patients with various previous illnesses than in healthy patients. These include people with diabetes mellitus, high blood pressure or cardiovascular diseases, overweight and elderly people, and it is precisely these who have a higher risk of severe Covid-19 infections anyway.

An explanation for the lowered vitamin D values ​​is obvious: “The most important vitamin D source is the formation in the skin through sunlight”, says the expert, “and in old age it only works to a limited extent” as older people often spend less time outdoors than younger people. This also applies to some chronically ill patients and especially those who are bedridden. People with low vitamin D levels tend to be older or more likely to have previous illnesses than patients with normal vitamin D levels. It is possible that with a Sars CoV-2 infection they become seriously ill more often – and not necessarily because of the low vitamin level at the same time.

Vitamin D levels as an indicator of higher risk

A Vitamin D deficiency alone is not the only factor that affects the severity Covid-19 infections but a person’s vitamin D levels could at least serve as an indication. If there is a deficiency, the risk of severe Covid-19 infections is possibly increased. The head of this research, Biesalski therefore recommends always determining the vitamin D level in the case of Covid 19 disease and quickly remedying a possible deficit.

“This is particularly recommended for people with one of the underlying diseases or for the elderly,” says the doctor. Vitamin D levels are often devastatingly low in people in retirement homes. People in the home office also stayed longer in closed rooms, which also contributes to poor vitamin D supply.

Too much vitamin D can be dangerous!

If you have a sufficient supply of vitamin D, an additional dose in pill form will not help. In the worst case, it can even be harmful. Because too much vitamin D increases the calcium level in the body.

And according to the Robert Koch Institute (RKI), this, in turn, can cause side effects such as abdominal cramps, vomiting or even kidney damage and potentially fatal cardiac arrhythmias. Since vitamin D is stored in the body, in addition to acute overdosing, creeping overdosing through nutritional supplements is possible, warns the RKI.

Soak up sunlight instead of swallowing pills

According to the RKI experts, if you expose your face, hands and arms to the sun two to three times a week between March and October, uncovered and without sun protection and soak up UV light with your hands, arms and face, you normally produce enough vitamin D. This is also enough to get through the winter in colder and darker climes.

In addition, we can also get much of the Vitamin D our bodies need from natural food sources including oily fish, beef liver, cheese, egg yolks, and mushrooms. Many breakfast cereals and milk and non-dairy alternatives are also fortified with vitamin D, as are infant formulas.


As we find ourselves in the midst of a global health crisis with the coronavirus pandemic, paying closer attention to the natural chemistry of our bodies is more important than ever. There is compelling evidence to suggest that having the optimal levels of Vitamin D can help to ward off and fight infections. It is also clear that the human body is far more complicated than just requiring one panacea type vitamin. Ensuring the correct levels of all vitamins and minerals is also important other things that we can do to ensure our bodies are in the best condition to deal with Covid-19. A good diet combined with regular exercise, albeit very simple are perhaps the best things we can do to support our health and well-being, with the so called “sunshine” vitamin  providing that little extra boost that we all need.