Vitamin D vs. Corona: If you take too much, you take great risks

Bonn –

If you want to do something for your immune system, you can buy extra vitamins from pharmacies, drugstores or the Internet. Better safe than sorry, especially in the Corona crisis. But exactly that, namely “safe”, is not the way for more immune power, the Bonn-based immunobiologist Prof. Ingrid Förster, expert for immune system and environment, emphasized in the EXPRESS interview.

Vitamin D in particular is slightly overdosed and, in addition to being healthy, is even harmful to health. The claim is circulating on the net: A vitamin D deficiency makes people more susceptible to the new type of corona virus, and the spread of corona can therefore be combated with the administration of vitamin D. The Bonn expert expressly warns against this idea.

“The fat-soluble molecule, which is related to cholesterol, can penetrate cells and change gene functions,” explains the scientist. This property makes it a double-edged sword. “It can both boost and suppress the immune response.”

Vitamin D vs. Corona? Only 20 percent come from food

Only 20 percent of vitamin D comes from food at all, and 80 percent is produced by the body due to the fact that UV radiation affects the skin. In exactly the right ratio for a healthy immune system. It is sufficient to expose the face, hands and arms uncovered two to three times a week to half the minimum sun-effective UV dose, the Federal Office for Radiation Protection (BfA) recommends.


Many rely on vitamin pills and special supplements during the corona crisis.

For people with skin type II (fair-skinned, not overly sensitive to the sun) this would result in 12 minutes. In summer, vitamin D is stored in fat and muscles for the low-light season.

Biologist: “You have to warn the public not to take vitamin D in an uncontrolled manner”

“In this respect, it is good if we all now move outside in the fresh air when the sun is shining,” says immunobiologist Förster. “But you should warn the public against taking vitamin D in an uncontrolled manner.”


Typical picture during the Corona period: queues in front of the pharmacies

She emphasizes: “Dietary supplements are not subject to any restrictions, and fat-soluble vitamins in particular can do a lot of damage. I would not take them without medical supervision. “

Incorrect dosage of vitamin D can lead to kidney damage

A doctor must first definitely determine that there is actually a vitamin D deficiency. The tablets required to specifically compensate for this rare deficiency are prescription-only in high doses and can, for example, cause kidney damage if used improperly. Also fat-soluble vitamin A, which is often packaged as “good for the eyesight” in vitamin mixes, can have positive and negative effects on the defense against infections. Overdosing on vitamin A can damage the skin and liver.

Read more here: Covid-19 – Is the Corona Virus Particularly Dangerous for Smokers?

Vitamin C is somewhat less problematic. Again, the immune researcher warns against claims circulating on the net that vitamin C can help cure corona based on experience in China. “How exactly vitamin C affects the immune system has not yet been clarified,” says Förster.

In contrast to vitamin D, vitamin C is water-soluble

The University of Bonn is one of the top research centers specializing in immunology and nutrition. “What we do know is that vitamin C inhibits the release of reactive oxygen molecules. But: This is more desirable for infections because it is an antibacterial mechanism. ”
Advantage of vitamin C: Unlike vitamin D, it is water-soluble. What the body does not use is eliminated. But vitamin C has a certain acidity, says Förster. In the worst case, lozenges can damage the tooth enamel.

“Vitamins are good and strengthen the immune system if they are ingested with food, they do not have such a good effect in tablets,” Förster said. “Vegetables with a particularly large number of secondary plant and fiber materials, less sugar and even higher quality than fruit.”

Biologist on Corona: High-dose vitamins do not “kill” the virus

She and her team are currently investigating receptors in the intestine that bind plant substances and protect the intestinal mucosa, using broccoli and Brussels sprouts as examples. She believes that high-dose vitamins “kill” a virus, but healthy nutrition with fresh products is guaranteed to be good for the immune system. “You can never eat too much of individual vitamins or minerals.”

This natural supply is an important building block for a strong, successful immune response, “which first triggers a defense reaction, then reduces itself.”

Remedy for Covid-19: Immediate quit smoking

The natural protective shield specifically against all kinds of respiratory infections, including Covid-19, is the best way to strengthen a stop smoking. “The best time to quit smoking is now,” advises the expert on the immune system and environmental substances. “Because cigarette smoke damages the lung tissue and makes us significantly more susceptible to respiratory infections.”

Unfortunately, the other tips from the immunologists at the University of Bonn cannot be bought or swallowed either:

  • Move: If we don’t move, the immune system tends to overheat unhealthily.
  • Avoid stress: Take a deep breath in the fresh air – this also helps against this immune power robber. Chronic stress, anxiety, depression, loneliness have been shown to weaken the immune system. While short-term, acute stress drives the immune system to produce more immune cells. Which – for a short time – also has a positive effect on otherwise healthy people.
  • Regular, adequate sleep: “The immune system recovers at night,” says Prof. Förster. “New immune cells build up during sleep.” This curve can even be measured over a 24-hour period. If you constantly treat yourself to less than six hours of sleep, the immune system also lacks regeneration: fewer new immune cells are produced.


Germans suffer from low levels of sun vitamin

How important is vitamin D for our health? This is the subject of heated debate among doctors. Some swear by vitamin D cures, others consider this an unnecessary trend. How is the vitamin D supply in Germany?

Vitamin D is the only vitamin that the body can produce itself. The so-called endogenous synthesis takes place in the skin instead of. Vitamin D acts like a hormone in the body and plays an important role in numerous metabolic processes. The “sun vitamin” is of central importance, for example, when ingesting calcium and bone health. However, the synthesis only works if sufficient UVB radiation is absorbed through the skin. According to experts, it is sufficient to spend around 15 minutes a day in sunlight and to shine it on the face and back of the hand. You play it safe if you spend a few minutes in the sun regularly in winter. In summer, you usually automatically get enough sun rays. However, there are exceptions (see below).

Nevertheless, many have a vitamin D value that is too low

This is because the body’s production of vitamin D does not work equally well for everyone. Some manage to compensate for the insufficient body’s own vitamin D synthesis through many stays in the sun. It doesn’t work with others.

According to studies by the German Society for nutrition (DGE) around a third of the population is undersupplied with vitamin D. Those affected have a blood serum concentration of less than 30 nmol / l 25-hydroxyvitamin-D – according to the DGE, they are considered to be inadequate. And just under 40 percent of Germans are only adequately supplied with vitamin D.

But vitamin supplements are not the solution

Overview studies on the effectiveness of artificially added vitamin D are sobering. The manufacturers’ promises that by taking vitamin D Cardiovascular disease and cancer can prevent or alleviate and osteoporosis preventive, could not be proven in a large number of studies. It is particularly sobering to discover that the meta-analyzes found almost no effect on bone health among those who took vitamin D via pills or capsules. According to current knowledge, taking vitamin D does not protect against osteoporosis, heart attacks, strokes or cancer.

It is believed that the widespread lack of vitamin D can also indicate poor health. Scientists suspect that low vitamin D levels are not the cause of chronic diseases, but that, conversely, aging processes and inflammatory processes lower the vitamin D levels.

In old age, the body loses the ability to synthesize vitamin D

Given these numbers, vitamin D cures are in vogue. But due to the data situation, most doctors and nutritionists are skeptical about the preventive use of high-dose vitamin D supplements. They advise you to go outdoors regularly so that the body can replenish its stores for the winter – especially after the winter. “Let the sun be well dosed on your skin,” recommends Isabelle C. Keller of the German Nutrition Society. Because over 80 percent of the vitamin D requirement is covered by solar radiation. No extensive sunbathing is necessary for this, the endogenous synthesis works even when the sky is overcast.

In the months between April and October, depending on your skin type, around 20 minutes outdoors are sufficient. However, at least parts of the body should be uncovered and free of sunscreen – but only for this relatively short period to avoid sunburn. The remaining 10 to 20 percent of vitamin D needs can be met through food, with oily fish such as mackerel or herring containing most of the nutrient.

Vitamin D test is not a cash benefit

So if you regularly stay outdoors, you don’t normally need to swallow any additional vitamin D supplements, says Keller. “We only recommend that certain risk groups who do not spend enough time outdoors go to the doctor and have their vitamin D levels determined.” In addition to infants who are additionally provided with vitamin D in the first year of life, the risk group includes above all the elderly and infirm, as well as people who, for other reasons, do little or nothing outdoors or have very dark skin. As a rule, insured persons must pay for the test, which costs around 30 euros, out of their own pocket.

The ability to synthesize vitamin D is lost in old age

“In old age, the ability to synthesize vitamin D through the skin decreases,” emphasizes Keller. Therefore, an additional vitamin D dose of at least 800 international units (IU) may make sense in people over 65. However, Keller warns against shearing all the seniors together: “Take the sprightly pensioner who works a lot in the garden or goes out regularly with the dog, he does not need a supplement.” It is different with sick, frail people.

Can artificial vitamin D harm?

The rule ‘a lot helps a lot’ does not apply to vitamins. At least not if you take them in the form of tablets. The effects of synthetic synthetic vitamins can still be determined through long-term studies. The tenor among nutritionists for all vitamins is that they should not be taken lightly in artificial form, because they can also harm. So you should only take vitamins, no matter what, in the form of tablets or powder if the doctor expressly recommends it. Overdosing vitamin D with food is not possible.

Important NOTE: The information is by no means a substitute for professional advice or treatment by trained and recognized doctors. The contents of cannot and must not be used to make independent diagnoses or to start treatments.