Research goes on about the effectiveness of vitamin D in preventing pathogen infections. What’s the new evidence and what are the associated recommendations?

In the ongoing battle of the COVID-19 pandemic, vitamin D has received increasing attention because of its potentially protective role against respiratory infections (read more here).

Several studies have determined that individuals who generally exhibit more severe symptoms of SARS-CoV-2 infection (i.e. the elderly, obese, and people with multiple pathologies) also have lower vitamin D levels. However, while this is a valid observation, it’s not sufficient alone, to prove that vitamin D intake protects against the pathogens responsible for respiratory infections such as SARS-CoV-2. For this reason, many studies have been initiated that we’ve already mentioned in a previous article, and now we can provide you with an update.

Studies on the Efficacy of Vitamin D in the Prevention of SARS-CoV-2 Infection

Among the various studies initiated in Italy, for example, we should mention the study initiated by the Academy of Medicine of Turin (and coordinated by Dr. Isaia and Dr. D’Avolio). This study (in Italian) receives the contributions of 61 physicians from many Italian cities, and it summarizes the benefits of vitamin D intake in the prevention and treatment of COVID-19. Moreover, it reports the doses of cholecalciferol (vitamin D3) recommended generally in the winter period, independently of SARS-CoV-2 infection.


In England, where historically the intake of vitamin D for preventive purposes is more widespread, a very large clinical trial has been initiated. More than 6,000 people have been enrolled in the Phase III Clinical Trial, being run by Queen Mary University of London, with the aim of determining whether vitamin D deficiency is associated with an increased risk of contracting COVID-19 and whether restoring normal vitamin D levels can counteract the infection.

Dr. Adrian Martineau of Queen Mary University of London said in a recent interview that several laboratory studies have demonstrated a role for vitamin D in response to viruses such as SARS-CoV-2, specifically by stimulating the immune system response.

In the CORONAVIT Trial, special attention is paid to those most at risk, such as the elderly and obese. The reason lies in the fact that the skin of the elderly is less efficient in producing vitamin D than the skin of young people, and therefore a supplement of cholecalciferol (vitamin D3) is strongly recommended. For the obese, on the other hand, it’s a matter of volume and distribution. In addition, the large fat reserves of the obese diverts vitamin D from overall circulation.

Could Vitamin D Play a Role in Vaccination Efficacy?

As we’re in an important phase of the vaccination cycle for SARS-CoV-2 infection, researchers have wondered whether vitamin D deficiency may be a hindrance — or conversely, its supplementation may in fact enhance vaccine efficacy.

A very recent study published in an influential journal, Immunotherapy Advances (Oxford University Press), states that vitamin D supplementation increases the immune response to the Varicella-Zoster Virus (VZV) vaccine. Particularly in the elderly, who have a less effective immune system, vitamin D supplementation reduces inflammation that results in a stronger antigen-specific response to vaccination. Therefore, vitamin D supplementation indirectly influences vaccination efficacy by acting on inflammation by reducing it.

Based on this observation, it can be argued that even in the case of SARS-CoV-2 vaccination, vitamin D supplementation may improve vaccine efficacy.

This post is also available in: Italiano


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