Vitamin D Deficiency and Brain Functions

*Vitamin D Deficiency*

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**Chapter 6**

**Abstract**

cognition

**1. Introduction**

Association of Vitamin D

A Systematic Review

*Jigna Shah and Sakshi Gurbani*

Deficiency and Mood Disorders:

The cells of our body comprise calcitriol (1,25(OH) vitamin D2), the active form of vitamin D, an integral biological substance that has an impact on a large number of biological processes. While high prevalence of vitamin D deficiency is detected in population worldwide, the reports from sun-soaked countries like India are also alarming to note that the deficiency of vitamin D as high as 70 to 90% is observed leading to several chronic diseases in the majority of people. Deficiency of vitamin D is observed not only because of low levels of vitamin D in the diet, less exposure to sunlight, reduced cutaneous vitamin D synthesis, but also due to consumption of particular medicines, undue alcohol intake, and tobacco smoking. Vitamin D is known to affect estradiol, dopamine, and pro-inflammatory cytokine levels, besides being involved in the regulation of mechanisms pertaining to hormones like glucocorticoids. When vitamin D binds to vitamin D receptors (VDR) present in the central nervous system, it is noted to be responsible for the regulation of brain neuronal functions. Low 25-hydroxy vitamin D levels are found to have a higher incidence of various mood disorders. This review focusses on vitamin D receptors, VDR gene mutations, and pathophysiology causing vitamin D deficiency disorders.

**Keywords:** vitamin D, VDR receptors, mood disorders, deficiency, insufficiency,

Vitamin D is an integral biological substance used to maintain bone health primarily, but it also plays its importance in several other biochemical pathways within the human body. Vitamin D, at the end of its metabolizing physiology, gets converted into an active hormone metabolite of vitamin D, i.e., calcitriol (1,25(OH)2 vitamin D), which binds to vitamin D receptors (VDR). Vitamin D enzymes present in the central nervous system are responsible for the regulation of cellular function in several tissues located in the body including brain neurons. Vitamin D comes in two main forms: the first form is vitamin D2 also known as ergocalciferol which is obtained from sources like mushrooms grown in UV light, dietary supplements, and fortified food, and the second form of vitamin D is vitamin D3 also known as cholecalciferol, obtained from oily fish and fish oil, liver, egg yolk, butter, and dietary supplements. Vitamin D2 and D3 are not equal when it comes to raising your vitamin D status. Both are effectively absorbed into the bloodstream. However, the liver metabolizes them differently. The liver metabolizes vitamin D2 into 25-hydroxy
