Vitamin D as an essential tool in the battle against COVID-19 and other virus infections

Vitamin D as an essential tool in the battle against COVID-19 and other virus infectionsVitamin D is essential for the immune defense but many of us are deficient of the nutrient during the dark winter period. The Danish Veterinary and Food Administration therefore recommends for everyone to take a vitamin D supplement in the winter months and that vulnerable population groups supplement all year round. Many people are unaware that being vitamin D-deficient contributes to new waves of COVID-19 and other types of viruses while increasing the risk of infections becoming complicated and life-threatening. This was demonstrated in multiple studies that have been published over the past 18 months. Leading scientists call for immediate action in terms of optimizing vitamin D levels in the population to help fight COVID-19 and other virus infections, simply because vaccines only have limited effect.

A COVID-19 infection normally starts by the virus infecting cells in the nose and spreading to the lower respiratory tract. Most people are able to reject the virus, or they may only develop mild to moderate symptoms. However, if the immune system is derailed, acute respiratory distress syndrome (ARDS) may develop in severe cases. One of the major reasons for this is cytokine storm and hyperinflammation in the epithelial cells of the lungs. Cytokine storm and hyperinflammation may also develop in the epithelial layer of blood vessels and other organs and lead to circulatory failure and death. In other words, it’s the immune system’s capacity that determines how well we are equipped to handle a virus attack. The immune defense is unable to function normally if there is too little vitamin D in the blood.

  • Coronavirus belongs to a group of viruses that can to cause disease in humans and animals.
  • Coronavirus can cause a common cold, SARS (2002), MERS (2012), COVID-19 etc.
  • Coronavirus belongs to the so-called RNA-viruses that tend to mutate into new variants.

Vitamin D and its role in the immune defense

Vitamin D is essential for the immune defense. It supports a number of its activities and helps it communicate. In our respiratory system, we have particularly many white blood cells, the macrophages that serve as storm troops by attacking airborne pathogens silently in the background without us noticing. They depend on vitamin D. The process is supported by antibiotic peptides in the airways that also need vitamin D.
In addition, the T cells (the special immune troops) in the blood need vitamin D to divide explosively and form an army of goal-oriented T cells that are needed to attack virus and establish our primary immunity. B cells that produce antibodies also need vitamin D.
If we have too little vitamin D in our blood it impairs several parts of our immune defense and we become easy targets for infections. Also, it can have a negative effect on the production of pro-inflammatory cytokines and their ability to communicate, causing the immune defense to set in with hyperinflammation which makes infections far more complicated and potentially life-threatening in worst case. A study that is published in the Journal of Medical Virology showed that low levels of vitamin D were associated with higher levels of proinflammatory cytokines in hospitalized COVID-19 patients.

  • You probably won’t know if your vitamin D levels are too low – but your immune defense will know for sure
  • Lack of vitamin D causes a weak and derailed immune system and increases the risk of infections and other complications

Large Israeli population study finds deficiencies in many vulnerable groups

In 2020, a large Israeli population study of more than 4.6 million people revealed that lack of sunshine and vitamin D can increase the risk of COVID-19 infection and new waves of the virus during the winter period. The scientists also mention that certain ethnic groups are more exposed because they get less sun exposure. This is the case with Jewish orthodox men, for example, because they wear long coats, hats, and have full beards. The same goes for female Muslims who veil their face and body. Face masks to prevent viruses from spreading also contribute to the problem because they reducing the sun’s contact with facial skin. The Israeli scientists therefore advise people to take vitamin D supplements during the winter period and recommend all-year supplementation for people in vulnerable groups.

Heavily increased rate of COVID-19 infections and deaths in places with little sunshine

Scientists from Northwestern University, Illinois, the United States, have analyzed data from hospitals and clinics in the USA, Germany, Italy, Iran, South Korea, Spain, Switzerland, Great Britain, and China. They found that far more patients die of COVID-19 in places where there is less sunshine. They also observed that patients with severe vitamin D deficiency are twice as likely to get serious complications and die of their disease.
In other words, it is not enough to look at hygiene, living conditions, the quality of healthcare, age distribution, and diet. It is also necessary to look at blood levels of vitamin D that can vary according to latitude, lifestyle, and other factors.

Data from several observational studies show that there is an inversely proportional relation between blood levels of vitamin D and COVID-19 infection risk/severity

Lack of vitamin D plus chronic disease increase your risk of hospitalization

For a period of four weeks, scientists at a hospital in Yerevan in Armenia measured blood levels of vitamin D in 300 patients that were hospitalized due to complicated COVID-19 infections. They found that the patients had alarmingly low levels of vitamin D and also noted that there was widespread vitamin D deficiency in the Armenian population. Moreover, the patients often suffered from elevated blood pressure, diabetes, smoking-related complications, and pulmonary diseases. The scientists observed that older people and people with a high BMI spent longer periods of time in the hospital and required more intensive care. Twenty-four out of the 330 patients died.
The low levels of vitamin D serve to show that vitamin D deficiency has a very negative impact on the immune defense and its ability to tackle virus infections.

82 percent of hospitalized COVID-19 patients lack vitamin D

Scientists from the University of Cantabia in Spain compared blood levels of vitamin D in 216 hospitalized COVID-19 patients and a group of healthy controls. They also looked at whether blood levels of vitamin D were related to the severity of the infection and the risk of dying. It turned out that 82.2 percent of the hospitalized patients lacked vitamin D, while 47 percent of those in the control group were vitamin D-deficient. Vitamin D deficiency is therefore very common.
On behalf of their study results, the scientists call for increased focus on vitamin D for the entire population, especially high-risk groups such as older people, nursing home residents, and chronically ill. The same goes for COVID-19 patients with a identified vitamin D deficiency.

Lack of vitamin D is related to serious complications and risk of death

According to a retrospective study of older COVID-19 patients, lack of vitamin d is linked to serious lung symptoms, prolonged disease course, and increased mortality risk. What makes the problem even worse is that vitamin D deficiencies are extremely common among seniors, nursing home residents, and other exposed groups of people. Many doctors and scientists therefore advise health authorities worldwide to include vitamin D supplementation in their campaigns as a necessary strategy to help fight COVID-19 and mutated versions of the virus.
The study aligns with a French meta-analysis in which it was demonstrated that vitamin D deficiency in older people increases their infection risk and the risk of the infection becoming complicated and potentially life-threatening.

  • 80 percent of hospitalized COVID-19 patients lack vitamin D
  • Severe vitamin D deficiency doubles your risk of dying of COVID-19
  • It is a big problem that vitamin D deficiency is so widespread among older people, people of color, chronically ill, overweight people, nursing home residents, and other exposed groups

Vitamin D supplementation of COVID-19 patients reduces their need for intensive care and lowers mortality rates

High-dosed vitamin D supplementation of hospitalized COVID-19 patients can save lives, according to a randomized clinical trial that was conducted at the University Hospital Reina Sofía de Córdoba in Spain. Seventy-six hospitalized COVID-19 patients were allocated to standard treatment alone or standard treatment in combination with high-dosed vitamin D supplementation. The scientists chose vitamin D in the form of calciferol (25-hydroxyvitamin D3) because it is easier and faster to use. Only two percent of patients in the vitamin D group required intensive care compared to 50 percent of patients in the non-supplemented group. There were no fatalities among the vitamin D-treated and everyone in this group was discharged without further complications.

High levels of vitamin D in the blood protect against COVID-19 and other respiratory infections

Blood levels of vitamin D should ideally be above the official threshold values in order to offer protection against COVID-19 and other respiratory infections. This is particularly true for people with dark skin. Lead investigator of the study, David Meltzer, PhD, who is affiliated with the University of Chicago Medical Center, was inspired by an earlier study from the beginning of 2020. In this study, it was observed that vitamin D-deficient participants who were given supplements of the vitamin had a much lower rate of respiratory infections compared with the participants that did not take supplements.

  • Blood levels of vitamin D are categorized as regular deficiency (below 30 nmol/L), insufficiency (30-50 nmol/L), and sufficiency (above 50 nmol/L)
  • According to many leading scientists, the optimal level is somewhere in the range of 75-100 nmol/L

 The Swiss Society for Nutrition and a panel of experts demand immediate action

A panel of doctors and professors in collaboration with the Swiss Society for Nutrition have pored over the scientific literature concerning nutrients and their role in a well-functioning immune system with particular focus on virus infections and the COVID-19 pandemic. In its white paper, the expert panel points to the fact that there is widespread vitamin D deficiency and it refers to over 1,500 published articles about vitamin D’s role in the immune defense. On behalf of the solid scientific documentation, the experts recommend a daily 50-microgram vitamin D supplement, a dose that is way beyond the official recommendations.
The panel also addresses the problems with widespread deficiencies of vitamin C, selenium, zinc, and omega-3 fatty acids that can contribute to new virus waves and complicated infections. It has been more than a year since the Swiss Society for Nutrition and the panel of experts authored the white paper and demanded immediate action. So far, nothing has happened.

Danes are advised to take vitamin D - but many are unaware of it

The Danish Veterinary and Food Administration recommends vitamin D supplementation for all people during the winter period and all-year supplementation for those who don’t get enough sun. It is also advised for children under the age of four years and exposed groups of people to take vitamin D all year round, but many people are unfamiliar with these recommendations. What is more, vitamin D supplements are not administered routinely like e.g. prescription medicine.

  • A blood test can show if you have optimal vitamin D levels
  • Remember that levels of vitamin D drop during the winter period unless you take a supplement

The actual need for vitamin D, the upper limit, and the quality of supplements

The actual need for vitamin D hinges on a variety of factors such as sun exposure, age, skin type, BMI, and chronic illnesses. EU’s Scientific Committee on Food has established the following safe upper intake levels for vitamin D:

  • 25 micrograms for infants aged 0 to 6 months
  • 50 micrograms for children aged six months to 10 years
  • 100 micrograms for children aged 11 years and older adults, including pregnant and breastfeeding women

The upper limits do not exceed the amount of vitamin D that the majority of people with fair skin is able to synthesize in the skin on a sunny day.
Vitamin D is available in high-dosed supplements with 20-100 micrograms of the nutrient. Vitamin D is a lipid-soluble nutrient. Therefore, the highest degree of absorption and utilization is obtained with vitamin D in oil in soft capsules. Keep track of how much vitamin D you get if you take several supplements.

We need magnesium for optimal utilization of vitamin D

When the UVB rays from sunlight synthesize vitamin D in our skin it is in the form of cholecalciferol (which is also available in supplement form). Cholecalciferol is not biologically active until it is converted by the liver into 25-hydroxyvitamin D3, the form of vitamin D that is measured in the blood. When vitamin D is needed for the immune system and all the other vitamin D-dependent functions it is converted into the active form called 1,25-dihydroxycholecalciferol D3. This conversion is handled by the kidneys, the white blood cells, and other cells. The study shows that magnesium-containing enzymes are needed to handle the two-step conversion process that takes place in the body’s cells.
In other words, a magnesium deficiency lowers both the activation of vitamin D and the many processes in which the vitamin takes place. Lack of vitamin D and/or magnesium has been observed in cardiovascular diseases and metabolic syndrome. This makes the patients increasingly vulnerable to COVID-19 infections and other types of viruses.

Vitamin D source Form of vitamin D and enzyme activity
Skin (sun exposure) Cholecalciferol
Vitamin D3
Made from a cholesterol precursor named 7-dihydroxycholesterol and the UVB rays from sunlight
Supplements Cholecalciferol
Vitamin D3
Liver Calcidiol/calcifediol
25-hydroxyvitamin D3 (measured in blood)
Synthesized by ways of an enzyme named CYP2R1
(requires magnesium)
Immune system
and other sites
Calcitriol (biologically active)
1,25-dihydroxycholecalciferol D3
Synthesized via the CYP27B1 enzyme
(requires magnesium)


Nihayet Bayraktar et al. Analysis of serum cytokine and protective vitamin D-levels in severe cases of COVID-19. Journal of Medical Virology 2021

Ariel Israel, Assi Circurel et al. The link between vitamin D deficiency and COVID-19 in a large population. Department of Research and Data, Division of Planning and Strategy. September 2020

Northwestern University. Vitamin D levels appear to play role in COVID-19 mortality rates. Science Daily. May 2020

Hutchings, N. et al. Patients hospitalized with COVID-19 have low levels of 25-hydroxyvitamin D. Endocrine. February 2021

José L Hernandez et al. Vitamin D Status in Hospitalized Patients with SARS-CoV2- Infection. The Journal of Clinical Endocrinology & Metabolism. October 2020

Cutolo M et al. Vitamin D and Lung Outcomes in Elderly COVID-19 Patients. Nutrients. February 2021

Moustapha Dramé et al. Relation between Vitamin D and COVID-19 in Aged People: A Systematic Review. Nutrients. April 2021

Marta Entrenas Castillo et al. Effect of calciferol treatment and best available therapy versus best available therapy on intensive care unit admission and mortality among patients hospitalized for COVID-19: A pilot randomized clinical study. The Journal of Steroid Biochemistry and Molecular Biology. October 2020

David O. Meltzer et al. Association of Vitamin D Levels, Race/Ethnicity, and Clinical Characteristics With COVID-19 Test Results. JAMA Network Open. March 2021

Nikki Hancocks. Diet and supplements: Swiss panel publishes COVID-19 recommendations. October 2020

Anne Marie Uwitonze, Mohammed S Razzaque. Role of magnesium in Vitamin D Activation and Function. The Journal of the American Osteopathic Association. 2018

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