Vitamin D has long been known to have an important, albeit not fully understood role in inflammatory processes. As inflammation is an expected symptom of viral airway infections, ex. influenza virus or novel coronavirus, it stands to reason that we should ask ourselves, whether it an intake of vitamin D would help in the fight against COVID-19. Many studies have been conducted on this topic. Some vitamin D benefits have been confirmed, but not all of them.

Vitamin D2 tablets

Because vitamin D’s activity is tightly connected with the presence of calcium in our body and its ability to be utilised, we can in no way expect to simply take a set number of drops and get exact results. Moreover, vitamin D intake can also be dangerous, so we should in no way begin taking supplements without prior consultation with a medical professional, who is familiar with our personal medical history and state.

The problem with lung and airway infections

With the flu, cold, as well as novel coronavirus infections, our immune system’s normal response is production of antibodies. When enough accumulate, the virus is contained and the body ready (i.e. immune) in case the infection reoccurs. However, sometimes things go awry.

Weakened immune systems may make an inadequate response to the pathogen. Small children and the elderly (i.e. 65 and older), people with chronic diseases (such as diabetes, high blood pressure, chronic pulmonary diseases), and/or smokers are especially at risk. The inadequate response can lead to deadly cases of pneumonia, which is difficult to treat, so it would be prudent to try to prevent it from ever developing.

How does vitamin D work?

The base function of vitamin D is maintaining correct blood calcium and phosphate levels. As it helps with utilisation of calcium in the body, and calcium being one of the main building blocks of bone, it has a direct effect on strengthening the skeletal system and prevents or at least slows down formation of osteoporosis. An increasing number of studies are finding, that it also has an important role in maintaining proper blood pressure and even preventing some forms of cancers (breast, colon and prostate), as well as autoimmune diseases.

During summer we generally don’t lack vitamin D

Vitamin D3 can be synthesised in our skin under UV radiation in the form of sunlight, or we can ingest it with food (ex. salmon), or with supplements. In the liver it is converted into its active form, which strengthens our immune system in three main ways:

  • Strengthening physical barriers (ex. strengthening the bonds between cells)
  • Boosting natural immunity, specific to each individual
  • Boosting acquired immunity, specific to each individual after getting over an infection

Vitamin D increases the activity of antimicrobial peptides in cells, i.e. the parts of the cells, that recognise foreign bodies (including viruses, fungi and bacteria), prevent their entry, as well as attempt their neutralisation. Experiments on mice have shown a significant decrease in the replication speed of influenza viruses, which gives the body more time to prepare for a fight against the intruder.

Chemical structure of vitamin D3

The body’s ability to form the active metabolite of vitamin D in the liver decreases with age, which could explain the increase of novel coronavirus complications with age. Less physical activity, and consequently less time in the sun, as well as taking some medication (such as some antibiotics, anti-inflammatory drugs, blood pressure reducers, corticosteroids, …) is also proven to decrease the production and activity of vitamin D. Subsequently, more and more doctors have begun advising taking vitamin D supplements to at-risk groups, especially people over 65, smokers, and the chronically ill, in a nut shell, people with a weakened immune system.

The list of people with a heightened risk of vitamin D deficiency includes everyone, who lives in places with short daytime (close to the north and south pole), people with nutrient absorption abnormalities (Chrohn’s disease, cystic fibrosis), people living in very cloudy areas and citizens of extremely polluted cities.

These individuals are also the most at risk for developing heavy symptoms when infected with the novel coronavirus.

During winter the body produces less vitamin D

The fact that there are more complications with novel coronavirus infections in the time, when we are exposed to the sun less, as opposed to the summer months, is additional evidence to the theory that vitamin D has an important role in the course of onset COVID-19. According to data from the American National Center for Health Statistics, around 70% of Americans are vitamin D deficient.

An additional problem is posed by the simple and decades known fact, that tanning in the sun is not considered healthy anymore.

Conclusion and disclaimer

The authors on this website are not medical doctors, nor are we conducting clinical research, subsequently we cannot and must not recommend additional intake of vitamin D, which can in some cases even pose a threat to the patient. The facts that the recommended daily intake differs from person to person, that there are multiple types of vitamin D in the form of dietary and medicinal supplements, and that vitamin D utilisation is dependent on many factors, tell us that we shouldn’t take vitamin D supplementation lightly. Even the differences between different vitamin D types (ex. D2 and D3) are significant and need to be considered.

However, by all means, a strong immune system in the case of any infection, even COVID-19, cannot hurt. This is why we recommend, that you seek medical consultation and craft a strategy for maintaining and boosting your immune system, including a healthy diet, enough sleep, enough physical activity, ceasing indulgence in bad habits, and yes, possibly even with dietary supplements.