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Vitamin D levels can determine whether COVID-19 is harmless or life-threatening

Vitamin D levels can determine whether COVID-19 is harmless or life-threateningVitamin D-deficient patients are twice as likely to sustain life-threatening complications in the wake of a COVID-19 infection, according to a study from Northwestern University in the United States, where scientists collected data from 10 different countries. It is worth making a note of the fact that vitamin D deficiencies are particularly common among older people of color, nursing home residents, overweight people, and chronically ill individuals, all of which are well-known risk groups. In the future fight against COVID-19 and other epidemics, good hygiene, hand sanitizer, isolation, and delayed vaccines are not enough. We must take the right measures to regulate our immune system with vitamin D, which can determine whether we reject the virus, contract a mild infection, or die of the subsequent, life-threatening cytokine storm and organ failure.

Scientists from Northwestern University, Illinois, US, have collected and analyzed data from hospitals and clinics in the United States, Italy, Iran, South Korea, Spain, Switzerland, Great Britain, and China. They found that substantially more patients died of COVID-19 in places such as Italy, Spain, and Great Britain where vitamin D deficiency is much more widespread.
The scientists hope that their study will help shed light on why COVID-19 develops into a life-threatening condition in exposed groups, and why the disease acts differently from one country to another. It is not enough to look at factors such as living conditions, hygiene, the quality of the health care systems, age distribution, and diet. One must also take into account such things as blood levels of vitamin D that vary on behalf of factors like latitude, lifestyle, and other variables.
In the Northern hemisphere, the synthesis of vitamin D in our skin in response to sun exposure during the summer period is the single most important source of vitamin D. In fact, it is no coincidence that virus infections such as COVID-19 occur during the winter period and taper off in in the summer. Still, many people are chronically vitamin D-deficient for other reasons such as too much time spent indoors, ageing, being dark-skinned, being overweight, or suffering from chronic diseases like diabetes and sclerosis.

An estimated one billion people worldwide have minor or moderate vitamin D deficiency.

Vitamin D boosts and regulates the immune defense

The American scientists could see a clear link between lack of vitamin D and increased COVID-19 mortality. By analyzing available patient data in the different countries, they also found a strong correlation between lack of vitamin D and an overactive immune defense that is likely to induce cytokine storm and hyperinflammation.
According to Vadim Backman, who headed the study, and several other researchers, it is cytokine storm and hyperinflammation that are responsible for the severe damage to the lung tissue that may cause acute respiratory failure. The condition, also known as ARDS (acute respiratory distress syndrome), causes life-threatening, secondary damage to the cardiovascular system and other tissues.

It is not COVID-19 as such that causes the weakest patients to succumb and die, it is the malprogrammed and overactive immune defense that is the problem.

Vitamin D sufficiency can reduce mortality by 50 percent

Based on the new study, Backman and his team of scientists assume that vitamin D plays a determining role in the fight against COVID-19, as vitamin D not only boosts our innate immune defense that tackles most infections but also keeps the immune defense on a tight leash, thereby preventing it from overreacting. In other words, having enough vitamin D in the blood can help protect the population against most infections and severe complications, including death caused by COVID-19.
According to Backman and his science team, the analyses also show that sufficient vitamin D status can reduce mortality by 50 percent. It will not prevent a COVID-19 infection but it will result in fewer symptoms and prevent the life-threatening complications that may turn lethal in worst case.

Lack of vitamin D affects the proliferation and severity of current and future epidemics.

Why COVID-19 has a greater impact on older people than on children

According to Backman, the relation between vitamin D and the immune system may also help explain why COVID-19 does not have such a strong impact on young children compared with older individuals. This is because the young children have not yet developed their adaptive immunity, including the T cells, that is more likely to overreact with cytokine storm and hyperinflammation
It should also be mentioned that older people produce less vitamin D because of their thin skin and are therefore more likely to become vitamin D-deficient. Also, many older people do not get enough sun, to begin with. Finally, cholesterol-lowering drugs (statins), which many older people take, block their vitamin D synthesis.

Scientists: Widespread vitamin D deficiency requires stronger supplements

This website has referred to several studies of vitamin D and the immune defense, including the recent Irish TILDA report from University of Dublin. The report, which is based on a larger population study of people from 50 years and older, has revealed that there is widespread vitamin D deficiency in Ireland, especially among older people and nursing home residents.
According to the TILDA report, the immune response also changes as we grow older. Older individuals tend to develop chronic low-grade inflammation – also known as inflamm-aging. Many chronic diseases like diabetes, asthma, and cancer are also characterized by chronic inflammation, which makes these patients more vulnerable. Having adequate vitamin D levels in your blood can protect you against virus infections at the same time as counteract potentially harmful inflammation that occurs in connection with ageing processes, different chronic diseases, and in situations where COVID-19 and influenza become life-threatening.
The scientists behind the TILDA report therefore advise all adults to take high-dosed vitamin D supplements, especially older nursing home residents, chronically ill, hospital patients, health professionals, and other exposed groups.

How much vitamin D do we need?

In Denmark, the reference intake (RI) level for white-skinned adults up to the age of 70 years is five micrograms. The Danish Health Authority recommends a daily 10-microgram supplement for pregnant women, infants, people with dark skin and individuals that do not get out in the sun enough. Nursing home residents and people from 70 years of age are advised to take 20 micrograms daily.
Many scientists claim that the actual need for vitamin D is a far more than the RI level, and their recommendations typically lie in the range of 30-100 micrograms daily to ensure optimal blood levels of the nutrient.
During the summer period, a lightly dressed person can easily produce 20-100 micrograms of vitamin D daily with sun exposure, but it is not as easy for older people and individuals with dark skin. It is not possible to produce too much vitamin D from sun exposure. Excess levels of the nutrient are stored in the liver for future use. Many people become vitamin D-deficient during the winter period because their vitamin D stores are emptied.
A person’s actual need for vitamin D depends on factors such as age, skin type, BMI, smoking habits, chronic diseases like asthma and diabetes, and possible use of cholesterol-lowering statins. According to the European Food Safety Authority (EFSA), the upper safe intake level for vitamin D is 100 micrograms daily.
Vitamin D is a lipid-soluble vitamin. It is absorbed best if you take it in some kind of oil in soft gelatin capsules.

  • Blood levels of vitamin D should be at least 50 nmol/L, while levels between 75-120 nmol/L are ideal.
  • In order to reach these levels, it is normally necessary to take a supplement in the period from October to May. For people who do not expose themselves to the sun in the summer, all-year supplementation is necessary.


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

Ali Daneshkhah et al. The Possible Role of Vitamin D in Suppressing Cytokine Storm and Associated Mortality in COVID-19 Patients. medRxiv April 30, 2020

Eamon Laird, Rose Anne Kenny. Vitamin D deficiency in Ireland – implications for COVID 19. Results from the Irish Longitudinal Study on Ageing (TILDA) April 2020

Will Chu. Could vitamin D play a role in coronavirus resistance? Research thinks so. NUTRA April 2020

William B. Grant et al. Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and Covid-19 Infections and Deaths. Nutrients 2020

William B. Grant. Vitamin D Supplementation Could Prevent and Treat Influenza, Coronavirus, and Pneumonia Infections. Nutrients 2020

D.M McCartney, D. G. Byrne. Optimisation of Vitamin D Status for Enhanced Immune-protection Against Covid-19. Irish Medical Journal. 2020

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