The advent of the global pandemic has sparked a debate regarding whether Vitamin D—present in abundance in oily fish, red meat, egg yolk, and of course, sunlight—has any association with SARS-CoV-2, and its severity. "Vitamin D is a well-researched immunomodulator molecule and its beneficial properties for bone growth are extensively documented. However, its impact on inflammation and respiratory illnesses is debatable, and is met with mixed opinions," explains Dr Charu Dutt Arora.
The fat-soluble vitamin is crucial for immune system health, and a deficiency in this nutrient may compromise immune response, increasing the risk of infection and disease. "Research supports the theory that low Vitamin D levels are associated with an increased risk of respiratory diseases including tuberculosis, asthma, and chronic obstructive pulmonary disease (COPD), as well as a range of viral and bacterial respiratory infections and decreased lung function," adds Dr Arvind Malik.
In a recent study that took place at the Nizam Institute of Medical Sciences, pulse Vitamin D (administered at 60,000 IU per day for 10 days, as per the Body Mass Index of the patient during Covid-19) showed significant improvement in inflammatory markers. In addition, a few other researches indicated that those with low levels of Vitamin D (less than 20ng/ml) have a 7.2% higher chance of contracting the Covid-19 infection. However, none of the clinical trials pointed towards any association with duration of hospital stay or severity of illness. (A study regarding the prevalence of low levels of Vitamin D among Covid-19 patients in India, and associated risk factors).
Another study suggested that patients hospitalised with Covid-19—who also had sufficient levels of Vitamin D present in their bodies—were at a decreased risk for adverse medical outcomes, and consequent death. In patients older than 40 years, those who had adequate levels of Vitamin D were 51.5% less likely to experience adverse outcomes, including hypoxia and death, as compared to Vitamin D-deficient patients. Besides, Vitamin D supplements have been shown to reduce mortality in older adults, who are in the high-risk category of developing respiratory illnesses such as Covid-19.
A Vitamin D deficiency is also believed to enhance a process known as the 'cytokine storm'—a severe immune reaction in which the body releases too many cytokines into the blood, too quickly. Cytokines are proteins that play an integral part in immune system functioning, and possess both pro-inflammatory as well as anti-inflammatory effects. A cytokine storm can occur as a result of an infection, autoimmune condition, or other diseases. It may also take place post an immunotherapy treatment. The de-regulated and excessive release of cytokines may lead to severe tissue damage, and can enhance disease progression and severity. In fact, it is 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.
While research on the correlation between Vitamin D and Covid-19 continues, evidence that Vitamin D supplements reduce the risk of developing Covid-19 is still limited. However, there is umpteen evidence available to support the fact that this nutrient has a positive impact on overall immune health and well-being. One must get their Vitamin D levels checked, and should consult their physician before consuming any medicine, irrespective of their Covid-19 status.