5 questions on the impact of vitamin D on corona

1. Must I take vitamin D?

‘Yes. Our skin produces vitamin D when we are outside. In the winter, many people remain indoors, which may cause a shortage of vitamin D. Currently, many people work from home, and a considerable part of our social lives are on hold, which means we spend even more time indoors. This leads to a weaker immune system and increases the chance of contracting infections such as a common cold, flu or COVID-19. Taking vitamin D is always a good idea in the winter, but now more than ever in times of corona. The Health Council recommends that high-risk categories such as the elderly, pregnant women, people with face-coverings and dark-skinned people supplement 10 microgrammes daily, which is generally considered a safe dosage.’

2. Okay, but an improved immune system does not offer 100% immunity from COVID-19, does it?

‘Indeed, it does not. It’s all a matter of chance, and not of individual cases. There are many indications that people who have a vitamin D deficiency are more severely affected by a COVID-19 infection. However, a double-blind study in Spain shows that taking vitamin D reduces the chance of a severe case of COVID resulting from a SARS-CoV-2 infection. This study was conducted among a small sample of 76 subjects. Of the 50 persons taking vitamin D, not a single one perished, and only one person required IC care. Of the remaining 26 persons who were not supplementing vitamin D, 2 patients died, and 13 were admitted to the ICU.’

‘This is, of course, just a small study. Still, it offers the first proof that vitamin D can help mitigate the disease. Normally, it requires several similar studies to reach a so-called meta-analysis. If that analysis shows a significant effect, it is “evidence-based” and may be accepted in the medical domain. It could, however, easily take several years before there are sufficient studies. Meanwhile, people will end up in ICUs and possibly die. So, although it may not have been irrefutably proven, taking a safe dosage of vitamin D during the winter and especially during this pandemic, can certainly not hurt.’

3. Great! So we can resume our lives and go to the gym and bars?

‘Hold on. No, that would not be wise. Vitamin D is not a super drug that allows us to pretend the pandemic is over. As is the case with many foodstuffs, the effect is small, and it takes a while before it becomes visible. The vitamin may reduce the effects of corona somewhat. Adhering to the RIVM guidelines remains essential.’

4. Why is there no scientific proof?

Savelkoul and other experts continuously speak of “strong indications”. There is not yet irrefutable scientific proof. Savelkoul: ‘That simply takes too long. It would take years to complete the different studies in a scientifically sound manner to substantiate the indications. There are already publications available in which the effect of vitamin D on the immune system is explained, and which show that vitamin D may reduce the risk of a SARS-CoV-2 infection and mitigate the COVID symptoms. These studies must be extended, but are already promising.’

5. Are there disadvantages to taking vitamin D?

‘No. It is a vitamin our bodies make. So vitamins supplemented through nutrition (fatty fish), or sunlight will not result in toxicity. This effect could only occur with extremely high dosages (in excess of 1000 microgrammes a day). Thus, there is no need to exaggerate: stick to between 30 and 50 microgrammes a day.’