There is growing interest in the role of vitamin D in the prevention, symptoms management and evolution of the novel Coronavirus infection. In recent weeks, the idea has been advanced that vitamin D deficiency can increase the risk of more severe COVID-19 infections and associated outcomes, based on current knowledge of the immune system-modulating effects of the vitamin. Vitamin D has been scientifically proven to play a critical role in modulating both the innate and adaptive immune system, mediating inflammatory responses, promoting tolerance towards one’s system and supporting lung function, among other benefits.
While no official recommendations have been made in this respect, empirical evidence would suggest that adequate blood levels of vitamin D may conduce to more positive outcomes in the novel Coronavirus infection, as is the case with other respiratory infections such as the common cold, especially as studies appear to suggest that a deficiency of the vitamin is conducive to poorer outcomes in infections in general. Coincidentally, some of the categories most at risk for severe forms of the novel Coronavirus infections and poorer outcomes are also statistically likely to be vitamin D-deficient (e.g. people over the age of 65).
Vitamin D immune system effects
Research reveals receptors for vitamin D as well as vitamin D-synthesizing enzymes are present in numerous different types of cells in the human body, most notably immune system cells. Immune system cells such as lymphochytes (B cells, T cells), antigen-presenting cells (macrophages, dendritic cells, B cells) have receptors for vitamin D and are able to convert the inactive form of vitamin D, 25(OH)D, into calcitriol (if it can’t be produced by the kidneys, as it normally would). They then use the active form of the vitamin for both adaptive and innate immune system-type responses, including antibacterial and antiviral responses, pro and anti-inflammatory responses etc. Vitamin D deficiency is believed to compromise immune system function, resulting in inadequate immune system responses that create susceptibility to infection (source). It can be inferred from current data that vitamin D deficiency can create susceptibility to novel Coronavirus infections, same as with other types of infections.
Vitamin D supplementation is effective against the common cold. Those deficient benefit the most from vitamin D supplementation. Vitamin D supplementation helps reduce both the incidence and severity of upper respiratory tract infections such as the common cold (source). Up to 15% of all common cold cases are caused by 4 human Coronaviruses, other than SARS-CoV-2. But SARS-CoV-2 also starts out as an upper respiratory tract infection, similar to the common cold, and only advances to the lungs in severe forms of the disease. It can be inferred from such data that adequate blood levels of vitamin D, or supplementation for those that are deficient, may potentially exert similar benefits in novel Coronavirus infections.
One of the more severe complications of COVID-19 is organ dysfunction, notably acute liver and kidney damage. Research reveals that vitamin D metabolism involves both liver and kidneys pathways. The liver hydroxylates vitamin D3 (colecalciferol) produced in the skin as a result of sunlight exposure, which results in the production of the inactive vitamin D form known as 25-hydroxyvitamin D or 25(OH)D, an inactive form of vitamin D. The kidneys further convert 25(OH)D to the circulating biologically active vitamin D form known as calcitriol. By impacting liver and kidney function, the novel Coronavirus affects the body’s use of vitamin D which ultimately impacts immune system function and potentially also disease outcomes.
Vitamin D makes the immune system more tolerant to itself, whereas a deficiency has been shown to occur together with increased autoimmunity (source). Growing bodies of evidence support the crucial role of vitamin D in the prevention of autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, type 1 diabetes or inflammatory bowel disease (source). Increased autoimmunity may be one of the factors behind the ‘cytokine storm’ events observed in COVID-19 that are conducive to more severe outcomes. Find out more about what the novel Coronavirus does to the body.
Studies have found that vitamin D deficiency is one of the caused behind obstructive lung diseases (source). COVID-19 starts out as an upper respiratory tract infection, in the nose and throat, but advances to the lungs and all of the lower respiratory system – in severe forms, it is known to cause pneumonia, lung tissue damage, loss of lung function and more serious complications that could culminate with fatalities. Given the impact of vitamin D deficiency on lung function, it could be inferred that adequate blood levels could lead to more positive outcomes in COVID-19.
In an individual participant data (IPD) meta-analysis of 25 randomized controlled trials consisting of a total 11 321 participants aged 0 to 95 years, vitamin D2 and D3 supplementation was reported to reduce the incidence of acute respiratory tract infections (in 96.6% of subjects) by at least one respiratory infection. Those deficient in the vitamin reported experiencing the most benefits as a result of supplementation. The findings appear to support the immune system modulating action of vitamin D and its immunological benefits for respiratory tract infections management and prevention, urging an exploration of the benefits of the vitamin with regards to COVID-19 management.
Risk categories for Coronavirus infection are known to include people over the age of 65, especially those who reside in a long-term care facility such as a nursing home, people with impaired physical mobility and those that are immobile and receiving treatment in healthcare facilities, people with obesity, most of which are likely vitamin D-deficient, at least to some degree, as a result of the nature of their health status. Coincidentally, vitamin D deficiency promotes susceptibility to infection which would explain, at least in part, why the bulk of severe COVID-19 cases and COVID-19 cases most prone to complications arise from certain categories of the population moreso than others.
Other risk categories may avoid the outdoors as a result of the nature of their conditions (e.g. severe asthma, severe seasonal allergies) or require prolonged hospital stays (e.g. people in advanced stages of AIDS, cancer, heart, kidney or liver disease). They would risk vitamin D deficiency which would cause them to also become more susceptible to infections, potentially including COVID-19. More frequent hospital admissions as well as longer hospital stays further increase infection risks with the novel Coronavirus.
Empirical evidence further shows there is a significant reduction in the number of upper and lower respiratory tract infections of viral origin during warm summer months, likely due to increased vitamin D production as a result of sun exposure as countless studies confirm the immune system-modulating action of vitamin D and its immunological benefits. The higher temperatures which reduce virus viability and consequently also infection rates may further contribute towards this effect.
Conclusion
- Does vitamin D help prevent Coronavirus infections?
The body of evidence reporting on the negative systemic effects of insufficient blood-circulating levels of vitamin D grows by the day. But while it is clear that vitamin D deficiency increases infections incidence, such as viral respiratory infection rates of the likes of the common cold, there is currently no official recommendation from health authorities to increase vitamin D blood levels through supplementation and exposure to sunlight in order to lower COVID-19 infection rates and reduce disease severity. But if vitamin D helps prevent other respiratory infections and builds up the immune system, it stands to reason that it would be one of the supplements to take right now, if not for Coronavirus, then for good overall health. Or make via exposure to sunlight.
- Is vitamin D good for Coronavirus infections?
Vitamin D remains an essential micro-nutrient which means it is essential for good overall health. Countless studies have reported on the benefits of vitamin D for immune system function, lung function and its role in reducing the incidence of respiratory tract infections such as the common cold time time again. In addition to this, vitamin D holds benefits for fertility in women, bone health, mental health and has even been found to help with bone pain, muscle pain, fatigue and alopecia or hair loss. Existing science-based evidence urges us to maintain an adequate intake of vitamin D, either through sun exposure or supplementation, or both, if not for COVID-19 prevention or management, then at least for the other unequaled benefits that the vitamin provides. A minimum of 15 to 20 minutes of sunlight exposure of the face, neck and arms per day and supplementation such as with cod liver oil or other fish liver oils are some of the best ways to get your vitamin D and build up your immunity for COVID-19, the common cold or just good health.
