A recent article came out linking low Vitamin D levels and psychotic disorders like schizophrenia.  The study was done in Northern Europe when low Vitamin D levels are common.  The investigators failed to showed (but wondered) if psychosis was caused by low Vitamin D.   Isolation indoors due to psychosis can cause sunlight deprivation and low production of Vitamin D.  Further research is called for:  brain function requires Vitamin D, prevention of schizophrenia is very desirable, and Vitamin D supplementation is so easy and safe.   Like fish oil supplementation, Vitamin D may end up another tool to use in at risk youth with attenuated symptoms of psychosis.

http://www.medscape.com/viewarticle/813637?nlid=37590_329&src=wnl_edit_medn_psyc&uac=27343DV&spon=12