Vitamin d deficiency in relation to psychiatric illness: A Unani conceptual review

Abstract

Vitamin D is most unique among all vitamins. The term ‘vitamin d’ is actually a misnomer, as Vitamin D is not a Vitamin but is the only vitamin which is a hormone, synthesized endogenouslyby the kidneys. Vitamin D is a seco-steroid hormone with multiple functions in the nervous system. Physiological brain mechanisms of vitamin D and its receptors include neuroprotection, antiepileptic effects, and Immuno modulation, possible interplay with several brain neurotransmitter systems and hormones, as well as the regulation of behaviours. Vitamin D insufficiency affects almost 50% of the population worldwide. An estimated 1 billion people worldwide, across all ethnicities and age groups, have a vitamin D deficiency (VDD). This hypovitaminosis D can mainly be attributed to lifestyle (for example, reduced outdoor activities) and environmental (for example, air pollution) factors that reduce exposure to sunlight, which is required for ultraviolet-B (UVB)-induced vitamin D production in the skin. Here we review the important role of the vitamin D neuroendocrine system in the brain and outline perspectives for the search and usage of novel neurotropic treatment to treat various vitamin D-related dysfunctions and psychiatric illnesses.