Coronavirus Infection and Vitamin D Supplements

It is now among the more frequently asked questions relating to COVID-19.  Some claim that vitamin D should be part of a supplement regimen to improve immune defenses and prevent COVID-19. Others claim that it reduces the severity of the disease and even aids with recovery. Vitamin D is not only important for bone health. It also has benefits for the cardiovascular system and immune function. It is the latter that may be the reason why vitamin D is being touted as an aid in the fight against COVID-19.

Does Vitamin D fight the coronavirus?

There has been ongoing discussions about the benefits of vitamin D for COVID-19. As with any infectious agent, the immune system plays an integral role in preventing infection as well as fighting the pathogen. It is no different with the current coronavirus (COVID-19). It is well known that immune health is not due to just a single nutrient. The immune system is complex and its health is a reflection of the overall health of an individual. Nutrition, exercise and other lifestyle factors can affect immune health.

Vitamin D cannot destroy the coronavirus (COVID-19) in the way alcohol does on surfaces or the way certain antiviral drugs can target some viruses. Therefore vitamin D supplementation cannot be viewed as a treatment for COVID-19. However, vitamin D is known for its immune benefits. It can have an immune-modulating effect and lower inflammation. This can be useful in the fight against COVID-19.

Why vitamin D may be useful for COVID-19

There are no double-blind, placebo-controlled studies to verify that vitamin D has a distinct benefit in COVID-19. Vitamin D deficiency is the second most common nutritional deficiency. It was therefore observed that nations known to have a higher incidence of  vitamin D deficiency had more severe case of COVID-19. In contrast, people in countries where vitamin D deficiency is less common did not show the same number of severe cases and deaths from COVID-19.

This is not conclusive evidence that vitamin D is effective in the fight against COVID-19. Some South Asians studies showed that vitamin D deficiency was more common in patients hospitalized with severe COVID-19 compared to patients with mild illness. It was also observed in previous studies that people with severe respiratory infections (not COVID-19) were more likely to have a vitamin D deficiency.

Is Vitamin D supplementation necessary?

While it is still unclear whether there is a link between vitamin D deficiency and severe COVID-19, treating any nutritional deficiency is always advised. Vitamin D can be produced with adequate sunlight exposure. It can also be sourced from foods and supplements. However, these is no scientific evidence suggesting that excessive doses of vitamin D is warranted.

During this period of the COVID-19 pandemic, every person should take every measure possible to improve their overall health. Nutrition and exercise are the first steps. Avoiding unhealthy lifestyle habits like smoking or excessive alcohol consumption are other important steps. Vitamin D is helpful in a person with a deficiency. People who tend to live in regions with limited sunlight are particularly at risk.

With prolonged lockdowns, the time outdoors is limited and this may put more people at risk of a vitamin D deficiency. Therefore supplementation can be helpful. However, it should not be used as a standalone measure to prevent COVID-19 or be seen as a ‘magic bullet’. The recommended mitigation factors like frequently washing hands with soap, avoiding touching the face, maintaining social distancing and wearing of face masks should also be practiced.

Who needs vitamin D for COVID-19?

Now that there is some association established between vitamin D and COVID-19 recovery, supplementation may be advisable for high risk individuals. Thus far it is known that the elderly and people with co-morbidities like diabetes, heart disease, chronic lung diseases and immune deficiencies seem to be at a higher risk of severe COVID-19 infection and death. Low sitamin D levels may not be a causative factor for severe COVID-19 although an association has been noted. Therefore high risk individuals in particular may benefit from vitamin D supplementation.

However, any person may benefit from vitamin D supplementation even if they are not considered to be in this high risk group. It is important to remember that vitamin D is important for overall health. Therefore supplementation will ensure that a person is getting enough of this micronutrient. There may be no signs of vitamin D deficiency among people who do have this condition. Without a blood test, it can be difficult to ascertain who has a vitamin D deficiency. Therefore moderate supplementation can be helpful for every person.

Always speak to a doctor or pharmacist to establish whether to start on vitamin D supplements. With sufficient sunlight exposure and adequate diet of foods rich in vitamin D, supplementation may not be necessary.

Sunlight or Food for Vitamin D

Although vitamin D supplements are convenient, there are also natural sources of this micronutrient. It can be sourced from food and certain foods are rich in vitamin D. This includes fish, particularly oily fish, beef liver and egg yolks. Vitamin D is also present in various other foods. However, dietary intake may not always be sufficient if a person does not consume a diet that is abundant with food that are rich in vitamin D.

Sunlight exposure is another natural way to acquire vitamin D. It is the ultraviolet light, particularly ultraviolet B (UV-B), that is necessary for the production of vitamin D. Regular sunlight exposure is key for vitamin D acquisition through this method. A person should spend anywhere between 10 minutes to 30 minutes in the midday sun at least a few times a week for adequate vitamin D production.

Despite the dietary and environmental sources, vitamin D supplements can be helpful. These supplements should not be used to replace other sources of vitamin D if available. Instead it should be taken to “top up” vitamin D in the body. High dose vitamin D supplements are not necessary for most people unless it has been prescribed by a doctor. A supplement containing the recommended daily allowance (RDA) of vitamin D is usually adequate.


  1. Does Vitamin D Protect Against COVID-19? Medscape
  2. Can Vitamin D Prevent COVID-19? Cleveland Clinic

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