Vitamin D: Role in chronic and acute diseases

Vitamin D is involved in bone health by promoting calcium absorption in the gut and maintaining serum calcium and phosphate concentrations, and by its action on bone growth and reorganization through osteoblasts and osteoclasts cells. Moreover, during the last three decades, novel actions of vitamin D have been discovered. Several systematic reviews and meta-analyses have shown links between serum vitamin D levels and non-communicable diseases. In line with these findings, a wide number of studies have suggested associations of vitamin D deficiency (VDD) with respiratory tract infections, osteoporosis, and other chronic and metabolic diseases such as obesity, metabolic syndrome, type 2 diabetes mellitus (T2DM), cancer, rheumatoid arthritis (RA), and inflammatory bowel disease (IBD). Vitamin D also exerts important actions in the clinical course of infectious and other acute diseases, particularly respiratory bacterial infections, tuberculosis, and virus infections, e.g., those generated by human immunodeficiency and SARS-CoV-2 (COVID-19) viruses. The present article aimed to update the role of vitamin D in chronic and acute diseases. Key points • To know the role of vitamin D in the prevention and treatment of non-communicable chronic diseases.• To understand how vitamin D deficiency is related to obesity, insulin resistance and metabolic syndrome, type 2 diabetes, cancer, rheumatoid arthritis, osteoporosis, chronic pulmonary obstructive disease, and inflammatory bowel disease.• To know the function of vitamin D in the prevention and treatment of acute infectious diseases of bacterial and viral origins, namely respiratory infections.• To understand the role of vitamin D in the prevention of HIV and SARS-Cov2 infections• To know how vitamin D status affects the course of critical illness diseases