A new study links vitamin D levels with the coronavirus pandemic and mortality rates. In the study of data from 20 European countries, it was discovered that low average levels of vitamin D correlated with high numbers of cases and death rates. While crude, this relationship is a significant demonstration of the protective factors provided by vitamin D.
It was noted by researchers that countries whose population presented with lower levels of serum 25(OH) D levels, such as Italy and Spain, experienced higher mortality from the coronavirus. The study showed a mean serum vitamin D level of 26 nmol/L in Spain, and 28 nmol/L in Italy. Women aged 70 and over in Italy were also found to have circulating levels below 30 nmol/L—the level at which vitamin D deficiency is determined.1 Alternatively, northern European counties, and particularly Scandinavian countries, had the lowest numbers of coronavirus cases as well as lower mortality rates compared to other European countries. The mean serum vitamin D level for these countries was 45 nmol/L in older people.1 A higher intake of cod liver oil, vitamin D supplementation, and fortified foods were identified as key factors.1
Vitamin D status deteriorates with age, at or around 70 years of age due to decreased sun exposure and cutaneous synthesis. A possible reason for the lower levels of vitamin D in southern European countries as seen from the study is less sun exposure (a preference for shade to strong sun), as well as a reduction of vitamin D synthesis due to skin pigmentation.1
Protective effects of Vitamin D
Vitamin D has been found to modulate macrophage response and prevent the release of too many inflammatory cytokines and chemokines.2
Another study noted that calcitriol exerted pronounced impact on ACE2/Ang(1-7)/MasR axis with enhanced expression of ACE2, MasR and Ang(1-7) generation.3 ACE2 is the host cell receptor responsible for mediating infection by the coronavirus implicated in the current pandemic.3 High levels of ACE2 are also associated with better outcomes for coronavirus disease, and that in the lung ACE2 protects against acute lung injury.4
As vitamin D has been shown to protect against acute respiratory infections, researchers will further study its ability to protect patients with the implicated coronavirus in varying degrees of severity.
1. Ilie PC, Stefanescu S, Smith, L. The role of vitamin D in the prevention of coronavirus disease 2019 infection and mortality. Aging Clin Exp Res (2020).
2. Helming L, Böse J, Ehrchen J et al (2005) 1alpha,25-Dihydroxyvitamin D3 is a potent suppressor of interferon gamma-mediated macrophage activation. Blood 106:4351–4358.
3. Cui C, Xu P, Li G et al (2019) Vitamin D receptor activation regulates microglia polarization and oxidative stress in spontaneously hypertensive rats and angiotensin II- exposed microglial cells: role of renin-angiotensin system. Redox Biol 26:101295.
4. Kuka K, Imai Y, Penninger JM (2006) Angiotensin-converting enzyme 2 in lung diseases. Curr Opin Pharmacol 6:271–276.