Influence of exercise and vitamin D on the immune system against Covid-19: an integrative review of current literature

Abstract

Respiratory infections of viral origin have become the leading cause of infectious diseases in the world. In 2020, the World Health Organization (WHO) declared a pandemic due to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Coronavirus Disease 2019 (Covid-19). The pandemic caused by the new coronavirus has challenged the entire global health system, since Covid-19 has a high rate of morbidity and mortality. The immune response to the virus depends on factors such as age, genetics, nutritional status, physical status, as well as environmental factors. Despite scientific advances, so far, there is still no specific therapy for the disease. Thus, this study aims to analyze the contribution of physical exercise and maintenance and/or supplementation of vitamin D to the strengthening of the immune system against viral infections, among them, Covid-19. Regular practice of moderate-intensity physical activity is responsible for promoting a reduction in the concentrations of pro-inflammatory cytokines (IL-6, TNF-α and IL-1β), as well as triggering the increase in the production of anti-inflammatory cytokines (IL-4 and IL-10). In addition, hypovitaminosis D predisposes to the development of chronic diseases and infections. Therefore, in patients affected by Covid-19, the maintenance of vitamin D levels contributes significantly to the 0prevention of the cytokine storm. Thus, the association between maintaining vitamin D levels and performing moderate-intensity physical exercise is responsible for strengthening the immune system and, therefore, triggering a defense mechanism against infections by intracellular microorganisms, in which SARS -CoV-2.

Keywords: Covid-19; Cytokine storm; Immune system; Physical exercise; Vitamin D.

Fig. 1

Vitamin D metabolization mechanism. Vitamin D is obtained through food, the action of ultraviolet light and exogenous supplementation. In the liver, it undergoes the action of the enzyme CYP2R1 (25-hydroxylase), being converted into 25(OH)D. When this molecule reaches the kidneys, it is converted by CYP27B1 (1-alpha-hydroxylase) to 1,25(OH)2D, the active form of the vitamin. Source The Authors

Fig. 2

Performance of vitamin D and physical exercise in the immune system. Vitamin D supplementation associated with physical exercise contributes to the reduction of the risk of upper respiratory tract infection, given that there is an increase in the levels of SIgA, TNF-α and catelecidines. On the other hand, there is a significant reduction in circulating levels of the pro-inflammatory interleukins IL-6 and IL-1β. Source The Authors

Fig. 3

Role of vitamin D in the control of Covid-19. Vitamin D is converted to 25(OH)D by the liver by the action of the enzyme 25 hydroxylase. Thus, the epithelial layer is maintained in order to provide, through the action of cathelicidins and defensins, a reduction in survival and viral replication. In patients affected by Covid-19, there is a lower incidence of severe forms of the disease in individuals who used vitamin D supplementation. Source The Authors

Fig. 4

Schematic representation of immunological changes triggered by physical exercise and vitamin D. Source The Authors