A few weeks ago the hypothesis was put forward by two doctors from Turin that a vitamin D deficiency could cause more severe complications in the course of the COVID-19 infection. Now, an article in the preprint phase, that is, awaiting publication, confirms this hypothesis with objective data. The research was performed by a team of scientists from Northwestern University (Daneshkhah et al, 2020).
Scientists have wondered why the virus is more aggressive in some cases. Explanations such as age, region or healthcare system have not been considered valid as different clinical courses have been observed in people of the same age or severe complications following infection occurred even in areas with a very efficient healthcare system. Instead, it has been noted that the factor that unites the most severe cases is the deficiency of vitamin D. In particular, it appears that a deficiency of vitamin D is connected with the so called cytokine storm. What does this mean? The novel coronavirus, when it enters the body through the upper airways, can be blocked by the immune system. If this does not happen, the virus continues and reaches the lungs. The scientists have observed that it is not so much the damage that the virus can cause in the lungs that causes serious reactions as the cytokine storm. The body reacts, with a delay, to the virus that have attacked the lungs by triggering an uncontrolled inflammatory reaction. It is this exaggerated immune response, namely the cytokine storm, that causes severe lung damage and an acute respiratory syndrome, the real reason for the complications. Well, an adequate level of vitamin D seems to ward off this excessive work of the immune system. This explanation is also confirmed by the observation that children seem less attacked by the novel coronavirus. In children, the so-called acquired immune system, which is the one that triggers the cytokine storm, is not yet developed while the innate one prevails, namely the first line of defense, the one that immediately enters the field in case of an infection.
As stated by doctors, however, this does not mean that now everyone should take a huge amount of vitamin D supplements as side effects may occur. You should always contact your doctor to evaluate the individual situation and remember that natural sources of vitamin D are the sun, but avoid taking it in the hours around noon, and some foods, such as eggs, cheeses, mushrooms, such as shiitake, or fish, like anchovies or mackerel.