The Role of Vitamin D in Protection against Viral Infections and the new Coronavirus
Without a doubt, vitamin D is important for strong immunity.
Although we have observed the benefits of this increasingly popular vitamin for years through the prism of protecting bone mineral density, today we know that it is a powerful anti-infective nutrient.
A study by Norwegian scientists published in 2009 compared the status of vitamin D in the population and mortality from influenza and pneumonia.
The research was at the level of one year and the last two decades of the 20th century.
In both periods (1980–1989 and 1990–1999), the mortality rate was very low during the period when status of this vitamin was at its peak.
This led them to think that the seasonal variations in the incidence of influenza are related to the host (human).
The host may influence them more than differences in virus strains from year to year.
The same strain of the virus appears to be present in hosts for extended periods, over two or more years.
However, the manifestation of the disease depends on the weakening of the host immune system.
Therefore, the authors hypothesize that seasonal variation in influenza mortality rates associates with seasonal variations in vitamin D status.
Sunbathing for Recovery
Researchers recorded the same strategy for the 1918-1919 pandemic flu.
Many years later, researchers discovered that the active form of this vitamin (1,25-dihydroxy vitamin D3) stimulates the production of cathelicidins.
Cathelicidinsplay a central role in innate immune defense.
Namely, people believe that the increased frequency of colds and pneumonia during the winter is associated with reduced exposure to sunlight.
This is one of the factors contributing to the seasonal health variations.
Consequently with decreased values of the active form of vitamin D in the blood.
Less vitamin D, more infectious diseases
Scientific studies have shown an association between low vitamin D concentrations and the incidence of multiple infectious diseases.
Especially infections of the upper respiratory system and enteroviruses, but also pneumonia, ear infections, dengue fever, hepatitis B and C and HIV infections.
The basic mechanism underlying the anti-infective effect is the effect on the expression of cathelicidin and beta – defensin 2 in phagocytes and epithelial cells.
Vitamin D shows efficacy especially in the case of enveloped viruses.
Those are influenza viruses and coronaviruses (which possess a lipid envelope with protrusions on the surface).
Despite a clear and documented association between vitamin D levels in the blood and the incidence of respiratory infections, there is still insufficient research.
This lack of research prevents a unanimous confirmation that supplementation of this vitamin prevents or helps cure viral respiratory infections.
Benefits of Supplementation
Researchers have conducted most studies on children and adolescents, and many of these studies have shown the benefits of supplementation.
Vitamin D replacement therapy in immunocompromised patients may reduce the need for antibiotics.
So, healthcare providers recommend monitoring and correcting poor vitamin status in these patients.
Positive effects of supplementation have also been observed in the supplementation of patients with Crohn’s disease for the purpose of preventing respiratory infections.
Studies clearly show that this vitamin undoubtedly forms a link in a chain of complex factors that contribute to the immune response.
Therefore, monitoring the concentration of this vitamin in the blood and maintaining optimal status is a strategy that may contribute to defense against respiratory infections.
Especially in the elderly and patients with a number of other diseases.
Can we link COVID-19 and vitamin D?
Based on previous research, we can hypothesize that good vitamin D status may reduce the risk of viral epidemics and pandemics in a number of ways.
Adequate levels of this vitamin are unquestionably important for maintaining bone mineral density and muscle mass and strength.
Poor vitamin D status associates with malignant, cardiovascular, autoimmune, and neurological diseases.
Also with chronic respiratory diseases, diabetes and hypertension.
It is these diseases that are associated with the highest number of deaths among COVID-19 patients.
The risk groups in the COVID-19 pandemic are the elderly and patients with chronic diseases.
These are precisely the groups in which researchers record low levels of this vitamin in the blood.
Furthermore, the outbreak of the epidemic occurred at a time when, due to seasonal variations, the population has the lowest levels of this vitamin in the blood.
Particularly at risk group with higher mortality and more severe forms of the disease are obese people.
Obese people particularly experience vitamin D deficiency because adipose tissue sequesters (stores) this vitamin.
Smokers experience a similar situation, and studies also record lower levels of this vitamin in their blood on average.
An important link in the chain
To the question “Can vitamin D strengthen the body to fight viral respiratory infections, flu and SARS-CoV-2 virus infection?” there is no unequivocal yes / no answer.
There are still not enough scientific studies to show that vitamin D replacement is an effective strategy for the prevention and treatment of viral infections.
However, if we take into account all previous knowledge and facts, it seems that the additional use of vitamin D makes sense.
Especially in at-risk groups such as the elderly and the chronically ill and people who are not exposed to sunlight.
In addition to prevention, the use of vitamin D may be useful in reducing the mortality rate from viral respiratory infections, possibly including COVID-19.
In addition, the use of vitamin D as an adjuvant for new vaccines against influenza viruses as well as other viruses should be considered.
Vitamin D is one link in a row.
Responsible behavior and strengthening the immune system through diet and smart choice of dietary supplements can contribute to the defense against the virus.
