Most people do not get enough sun exposure in the 21st century. Because of this, many people are deficient in vitamin D.
Made for you
The vitamin D receptor is found in 900 genes in the human body, an appreciable part of the human genome. The brain is filled with vitamin D receptors and proteins that are turned on by vitamin D.
The good stuff
Proper vitamin D levels may boost mood (1), support immunity (2, 3), and build healthy bones (4).
(1) Vitamin D and the Immune System, J Investig Med. 2011 August ; 59(6): 881–886.
(2) 1,25-Dihydroxyvitamin D3 Restrains CD4+ T Cell Priming Ability of CD11c+ Dendritic Cells by Upregulating Expression of CD31, Front. Immunol., 28 March 2019.
(3) Vitamin D and Depression in Women: A Mini-review, Mohamed Said Boulkrane, Julia Fedotova*, Valentina Kolodyaznaya, Vincenzo Micale, Filippo Drago, Annemieke Johanna Maria van den Tol, Denis Baranenko, Current Neuropharmacology, Volume 18 , Issue 4 , 2020.
(4) Vitamin D and Bone, Curr Osteoporos Rep. 2012 June ; 10(2): 151–159.