A potentially underestimated vitamin could be a low-cost ally in the battle against SARS-CoV-2 infection. What is the evidence for the health benefits of vitamin D in humans, and why is it not popularized as a simple prevention aid against infection?
Everyone knows about vitamins, and also that they’re distinguishable by letters and sometimes numbers. Since the outbreak of SARS-CoV-2, we’ve been hearing more and more about vitamin D. Let’s try to better understand what it is.
What is vitamin D?
Vitamin D represents a group of molecules; the most important of which are vitamin D3 (or cholecalciferol) and vitamin D2 (or ergocalciferol).
Vitamin D3 is produced in the skin, from cholesterol, through a chemical reaction that depends on sun exposure. However, both vitamin D3 and D2 can be taken through both diet and supplementation. For example, fish (e.g. herring, salmon and sardines), liver and egg yolk are quite rich in it, not forgetting mushrooms and some types of chocolate.
What are the beneficial effects of vitamin D?
Vitamin D is essential for calcium and phosphate homeostasis, and is crucial for the growth and maintenance of our bones. In this regard, the known effects are:
- Promotes the absorption of calcium and phosphate in the intestine
- Promotes the deposition of calcium in the bones
- Promotes the renal reabsorption of calcium and phosphorus
- Maintains cartilage trophism
Returning to the interaction between vitamin D and SARS-CoV-2 infection, we can find much scientific evidence in favor of the anti-infective effects of vitamin D, starting from tuberculosis. Among other things, the number of scientific publications on this topic has increased enormously in recent months, as evidence of increasing scientific interest. Here are some examples:
- A study conducted in South Korea demonstrated reduced vitamin D values in patients with acute pneumonia.
- In patients with inflammatory bowel disease, it was shown that the administration of vitamin D3 reduced (by two-thirds) the incidence of upper respiratory tract infections.
- The immunomodulatory role of vitamin D and its antagonistic effect on viral replication in the respiratory tract have long been known.
There are also many studies on the effect of vitamin D on the prevention of SARS-CoV-2 infection, and also on the deficiency of the same vitamin in cases of COVID-19, confirming that vitamin D deficiency paves the way for infection.
People in Northern Europe, who are less likely to be exposed to sunlight than people closer to the Mediterranean, take vitamin D regularly, especially in food form. In a recent article, the UK government announced the free distribution of vitamin D to the population, in order to prevent the spread of SARS-CoV-2 infection.
In addition, a study has recently begun at Queen Mary University of London, called CORONAVIT that aims to study the role of vitamin D as a protector against COVID-19. The study will involve 5,000 people and will go toward correcting the lack of vitamin during the winter period.
Why does the Ministry of Health not promote the intake of vitamin D?
The official answer is that there is not yet enough robust evidence in favor of the effectiveness of vitamin D in preventing SARS-CoV-2 infection. However, as we’ve seen, work published throughout the past decade demonstrates the benefits of vitamin D on several diseases, and also on respiratory tract infections; so even if not directly related to SARS-CoV-2, one must wonder why its intake is not recommended. Moreover, being a low-cost molecule and without side effects, we don’t see the reason for not taking it regularly, especially by the elderly population that’s statistically the group with the greatest deficiency.
In conclusion, since we know that vitamin D is naturally synthesized when we expose ourselves to the sun, in compliance with safety measures let’s not miss a “sun bath”, maybe after eating some good fish and every now and then some egg yolk.
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