There have been many headlines recently about the importance of vitamin D during the corona virus 19 pandemic. What is evidence behind the headlines, and what does it all mean?
The virus which causes Covid 19 is called SARS-CoV2 or corona virus 19 (a type of corona virus), which enters cells via a special receptor called Angiotensin Converting Enzyme 2 (ACE2) Receptor. This receptor is predominately found on lung and to a lesser extent heart cells, explaining why the virus causes mainly lung and some heart problems.
ACE2 Dysregulation and Cytokine Storms
Once the virus has entered the host cell, it takes control of it, instructing it to manufacture more virus. This means that the ACE2 receptor becomes down-regulated, which has the effect of dysregulating an important system in the body called the renin-angiotensin system (RAS). An imbalance in this system is linked with a cytokine storm, where large numbers of white blood cells are activated; they produce messengers (cytokines) which coordinate the immune response, which activate more white blood cells. This creates a positive cycle and leads to the ‘cytokine storm’ instead of a more controlled immune response. This is over reaction of the immune system, leads to Acute Respiratory Distress Syndrome (ARDS), and why people have needed additional oxygen, and to be ventilated.
The Important Role of Vitamin D in Lung Health
Chronic vitamin D deficiency has been associated with increased risk of formation of lung fibrosis via activation of the RAS system.
Vitamin D is known to have an important role in lung function and decreased risk of respiratory tract infections, in people with chronic obstructive pulmonary disease (COPD), cystic fibrosis and other chronic lung conditions.
Low vitamin D has also been observed in a high proportion of patients with ARDS in intensive care prior to this pandemic. Additionally in rat models, vitamin D supplementation has been demonstrated to improve acute lung injury, acting partly via the RAS system. Vitamin D also has a direct anti-inflammatory response through specific white blood cells (T-cells).