When your body does not receive enough vitamin D, either due to a lack of sunlight or a poor diet it causes the occurrence of vitamin D. When exposed to sunlight, your skin can produce vitamin D; however if you live in a cold country with limited access to the sun or lead a sedentary indoor lifestyle, you may have low vitamin D levels. Vitamin D is in charge of calcium and phosphate metabolism as well as maintaining a healthy mineralized skeleton. It is also referred to as an immunomodulatory hormone. The active form of vitamin D, 1,25-dihydroxy vitamin D, has immunologic activities on multiple components of the innate and adaptive immune systems, as well as endothelial membrane stability.

There are possible links between vitamin D and protection from cancer, heart disease, bacterial and viral infections, COVID, and others. Vitamin D may decrease the growth of tumor cells, help with infections, and decrease inflammation.

Vitamin D builds immunity and helps to fight infections by modulating immune cell activity, which triggers an antiviral response. A vitamin D deficiency can impair immune responses and increase the risk of infections and diseases. In fact, this vitamin is so essential to immune function that lower vitamin D levels have been linked with increased susceptibility to infections, diseases, and immune-related disorders.

The implications of vitamin D deficiency for the immune system have been made apparent in recent years, and within the setting of vitamin D deficiency, increased susceptibility to infections, as well as diathesis, appears to occur in genetically susceptible hosts with autoimmunity. For instance, lower vitamin D levels are associated with increased risks for respiratory diseases, including tuberculosis, asthma, and chronic obstructive pulmonary disease, and for viral and bacterial respiratory infections. Appropriate vitamin D levels are associated with lower risks for inflammatory diseases, such as type 1 diabetes and multiple sclerosis, and lower rates of acute respiratory infections.

Vitamin D also can help protect us against infections (including COVID) and serious diseases such as cancer, cardiovascular and respiratory diseases, diabetes, and dementia. Based on vitamin D’s protective effects on subjects at risk for chronic diseases, including cancer, cardiovascular diseases (CVD), respiratory tract infections, diabetes, and hypertension, one might speculate that supplementation with vitamin D and associated increases of serum vitamin D levels higher than 50 ng/mL (125 nmol/L) might have a beneficial effect on the reduction in incidence and severity of several viral diseases, including COVID-19. Vitamin D did not lower the risk of acute respiratory tract infections, but it might slightly decrease symptom duration.

--- Dr.Sathyanarayana, General Physician, Kamineni Hospitals, Hyderabad