Vitamin D role in COVID-19

Vitamin D is a very popularly known vitamin, thanks to its role in bone health. It is a fat soluble vitamin that actually plays a number of critical functions apart from maintaining bone health. It is very important in maintaining a healthy immune system.  Research studies show that vitamin D has a tendency to reduce cancer cell growth, help control infections and reduce inflammation. Many of our body’s organs and tissues have receptors for vitamin D, which suggests important roles for vitamin D beyond just maintaining bone health, and scientists are actively investigating other possible functions & Vitamin D role in COVID-19 is one of them.

Can vitamin D lower your risk of COVID 19 ?

There is a lot of research going on about Vitamin D role in COVID-19. Some research has proved that having healthy levels of vitamin D can help to keep your immune system healthy and may protect against respiratory illnesses in general. One of the most commonly observed conditions that affects immunity is that the Vitamin D deficiency has been linked to the onset of COVID-19 and the alteration of course of the disease in patients and is also thus being explored as a potential drug supplement.

Vitamin D role in COVID-19
VITAMIN D3 supplement/Cholecalciferol

How does Vitamin D affect immunity ?

Vitamin D plays a major role in promoting immune response as it has both anti-inflammatory and immunoregulatory properties, and is thus very important for the activation of immune system defenses. Vitamin D or calciferol is an immunomodulatory substance & thus has a tendency to stimulate or suppress the immune system as needed to help the body fight cancer, infection or other diseases.

Vitamin D is known to enhance the function of immune cells which includes T cells(adaptive immunity) and macrophages(innate immunity), that protect your body against pathogens.

In fact, the vitamin is so important for immune function that low levels of vitamin D have been associated with increased susceptibility to infection, disease, and immune-related disorders.

So maintaining a required level of vitamin D (between 30–60 ng/mL (75–150 nmol/L) is utmost for the proper functioning of our immune system which is our body’s first line of defense against infection and disease.

 Vitamin D has been reported to highly influence respiratory health. Deficiency in vitamin D has been found to have a close association with decreased lung function. Deficiency in vitamin D is also known to increase the risk of respiratory diseases like tuberculosis, asthma, flu and chronic obstructive pulmonary disease (COPD), as well as viral and bacterial respiratory infections.


Vitamin D is a crucial vitamin for proper immune function. A Vitamin D deficiency may compromise immune response and increase your susceptibility to infection and disease.

Vitamin D role in COVID-19, Can Vitamin D protect against COVID-19?

A good amount of research is going on about Vitamin D role in COVID-19 & some studies have investigated the effect of vitamin D deficiency on the risk of contracting COVID-19 & also the effect of vitamin D supplements in helping the fight with COVID- 19.

Talking about the first case, research has already shown that vitamin D deficiency may harm immune function and make you more susceptible to developing respiratory illnesses.

Also, some studies do give an indication that vitamin D supplements can enhance immune response and protect against respiratory infections in general.

A recent study that included 11,321 people from 14 countries demonstrated that supplementing with vitamin D decreased the risk of acute respiratory infections (ARI) in people who were Vitamin D deficient and also who had adequate levels of vitamin D.

How to take Vitamin D for Immunity?

Another notable factor found in this study was that vitamin D supplements were most effective at protecting against ARI when taken daily or weekly in small doses and were found to be less effective when taken in larger, widely spaced doses.

Vitamin D supplements have also been shown to reduce mortality in vulnerable older adults, who are most at risk of developing respiratory illnesses like COVID-19.

To understand this strong immune effectiveness of vitamin D, its direct effect on modulating the immune pathways should be considered. The first part here is that vitamin D deficiency is known to enhance a process known as “cytokine storm” .

Cytokines are proteins which are an integral part of the immune system. They can have both pro-inflammatory and anti-inflammatory effects and play a crucial role in protecting against infection and disease.

However, cytokines also have a tendency to induce tissue damage under certain circumstances.

A cytokine storm refers to the uncontrolled release of pro-inflammatory cytokines which may take place in response to infection or other factors. The dysregulated and excessive release of cytokines leads to severe tissue damage and thus enhances disease progression and severity.

It is actually a major cause of multiple organ failure and acute respiratory distress syndrome (ARDS), as well as an important factor in the progression and severity of COVID-19 as the uncontrolled & non-specific inflammation and cytokine release can cause catastrophic injury to the lungs and other vital organs.

In severe cases of COVID-19, patients have been found to release large numbers of cytokines, particularly interleukin-1 (IL-1) and interleukin-6 (IL-6).

Vitamin D Deficiency and Cytokines

Vitamin D deficiency has been found to be closely associated with reduced immune function and has a tendency to enhance the cytokine storm.

A principal defense against uncontrolled inflammation & cytokine storm, is provided by T regulatory lymphocytes (Tregs). Treg levels have been reported to be low in some cases of COVID-19 patients, and were reported to be ‘markedly lower in severe cases’. 

Research has proved that a vitamin D deficiency may increase the risk of severe COVID-19 complications and vitamin D supplementation may reduce complications related to cytokine storms and uncontrolled inflammation in people with COVID-19.

Several clinical trials are currently investigating the effects of vitamin D supplementation (at high dosages of up to 200,000 IU) in people with COVID-19.

Many people across the globe are deficient in vitamin D, especially older individuals who are most at risk of developing serious COVID-19-related complications.

It’s a good idea to get your vitamin D tested regularly every 6 months to determine whether you have a deficiency in this important nutrient. This becomes even more important during winter months.

Depending on the blood levels, supplementation with 1,000–4,000 IU of vitamin D per day is typically sufficient for most people except the few severe deficiency cases.

Recommendations on what is an optimal vitamin D level vary, most experts agree that optimal vitamin D levels do lie between 30–60 ng/mL (75–150 nmol/L).


Vitamin D plays many important roles in our body, which includes maintaining a healthy immune system.

Research studies suggest that supplementing with vitamin D may protect against respiratory infections & COVID 19.

Sufficient vitamin D levels may help to decrease the severe complications in COVID-19, however more research is needed to support this data.

FAQ(Frequently Asked Questions)

What are Vitamin D deficiency symptoms ?

Bone pain, muscle weakness, fatigue, decreased immunity & falling sick more often, depression, hair loss, not sleeping well & loss of appetite.

Which vegetable is high in Vitamin D ?

Apart from fortified foods, mushrooms are the only sufficient non animal source of Vitamin D.

What are Vitamin D2 & Vitamin D3 ?

Vitamin D2 & Vitamin D3 are equivalent forms of Vitamin D & differ only in their sources. Vitamin D3 is only found in animal foods, whereas D2 comes from plant sources and fortified foods. Vitamin D2 is cheaper to produce & is thus commonly found in fortified foods.

How often should I have my Vitamin D levels checked ?

It should be done every 6 months or atleast once a year.

When should I test my Vitamin D levels after supplementation ?

It should be done three months after supplementation for an accurate measure of how well the supplement has replenished the whole body’s Vitamin D level.

My name is Amanpreet Kaur Samra. M.S. Biochemistry. I'm the founder and writer of this blog. I have been teaching Biochemistry for a good number of years. I started this blog because I have always been very passionate about writing, in particular about Nutrition and Healthy Weight Loss.

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