Should we be paying attention to our vitamin D intake?
Written by Nikoletta Skwarek
Mineral homeostasis, bone formation and respiratory robustness: what do they all have in common? Vitamin D. A molecule that is so often overlooked by many may yet prove to be an important factor in combating the Covid-19 pandemic.
A systematic review by Yisak and colleagues published in January proposed that blood vitamin D levels correlate with the risk and severity of Covid-19 across 7 out of 9 (77.8%) large studies. Perhaps now is the right time to reach into our supplements cupboard more so than ever.
Vitamin D is a lipid-soluble molecule present in two formats – ergocalciferol (D2) and cholecalciferol (D3), and is a precursor to a bioactive steroid hormone, calcitriol. True to its many names, ultraviolet B radiation from the sun is required for the production of vitamin D in our bodies. This mechanism is so effective that in the 1920s, pulmonary tuberculosis patients were prescribed sun exposure as a treatment. We also source about 20% of our vitamin D from our diet, mainly through fish, eggs and dairy. Our general consumption has been on the rise according to the Joint Research Centre of the European Commission, yet scientific reports are still calling vitamin D deficiency a pandemic. This is especially the case in Europe, where up to 40% of people do not have sufficient levels of vitamin D, mainly from the lack of sunshine. If you needed another reason to complain about the weather, here it is.
This collective insufficiency is particularly problematic now in 2021 due to vitamin D’s relationship with infectious diseases, including influenza, respiratory infections and as it happens – coronavirus. This particular molecule functions as a nutrient, hormone and as an immunomodulator. Deficiencies increase inflammation and deregulate the immune system, linking them to many autoimmune diseases on top of the aforementioned respiratory diseases.
How does this easily forgettable compound achieve big results? Turns out the majority of our immune cells are equipped with Vitamin D Receptors (VDRs). Many of these also express an enzyme, 1-alpha-hydroxylase (also known as CYP27B1), which is involved in the regulation loop of vitamin D activation. Simply put, the presence of calcitriol increases the efficiency of our first line of defence against pathogens, the innate immune system. When pathogens are detected, our immune cells turn up their expression of both VDRs and CYP27B1, allowing for increased production of calcitriol, thus self-regulating protective abilities. The involvement of vitamin D does not end there – calcitriol also modulates antimicrobial peptide production and strengthens the physical barriers to infection.
It is no surprise then that one of the papers examined by Yisak and colleagues found that low vitamin D increased the risk of Covid-19 infection, on top of predicting higher severity and mortality in patients. Lungs of patients with lower vitamin D may lack the support they need to even stave off the highly transmittable virus, moreover to efficiently fight it. The most hopeful news: treatments with a precursor of calcitriol decreased the severity of infection to the point of preventing ICU hospitalization 49 out of 50 (98%) patients, whilst 13 out of 26 (50%) of untreated patients had to be admitted.
Is vitamin D the ‘be all and end all’ for prevention and treatment of coronavirus? Most likely not (so don’t throw away your masks yet), but research into this may yet give us a much-needed edge in this prolonged and tiresome fight. Whether you trust this or not, perhaps we should err on the side of caution and include vitamin D supplements in our next online shopping sprees. Your body will definitely not object to a helping hand in keeping you nice and infection-free this winter.