Vitamin D: Extra-skeletal effects

There is a growing concern of vitamin D deficiency and its relationship with several extra-skeletal pathological states, ranging from immune disorders (systemic lupus erythematosus, type 1 diabetes mellitus, multiple sclerosis, inflammatory bowel diseases, and rheumatoid arthritis), cardiovascular disorders (coronary artery disease, atherosclerosis, and hypertension), infections (viral and bacterial), endocrine disorders (growth failure, infertility in males, metabolic syndrome, and type 2 diabetes mellitus), neuro-psychiatric, and neuro-degenerative disorders, renal disorders, chronic lung disorders to cancer. Besides its positive effects on the musculo-skeletal system, vitamin D has shown to take an active part in the regulation of cellular proliferation, differentiation, apoptosis, and angiogenesis. It has been shown to control approximately 3% of the human genes directly or indirectly. Although there is a strong body of evidence toward implication of vitamin& D deficiency with several extra-skeletal disorders, it remains unclear if vitamin D supplementation may slow down, halt or even reverse the disease processes. This review aims to discuss the potential associations of vitamin D with various extra-skeletal disorders.