Abstract: We propose vitamin D plays a role in mental illness based on the following five reasons:
1. Epidemiological evidence shows an association between reduced sun exposure and mental illness.
2. Mental illness is associated with low 25-hydroxyvitamin D [25(OH)D] levels.
3. Mental illness shows a significant comorbidity with illnesses thought to be associated with vitamin D deficiency.
4. Theoretical models (in vitro or animal evidence) exist to explain how vitamin D deficiency may play a causative role in mental illness.
First, we review recent evidence concerning the hitherto unexpectedly high human requirements for vitamin D. Then, we briefly review the physiology, toxicology, and evidence for widespread vitamin D deficiency.
Vitamin D3 and Solar Power for Optimal Health Find out how vitamin D is essential for proper brain function! After that we review epidemiological evidence that mental illness has increased as humans have migrated out of the sun followed by additional epidemiological evidence that associates vitamin D deficiency with mental illness. Studies associating season of birth with mental illness are briefly reviewed. Two small reports studied the association of low 25(OH)D levels with mental illness and both were positive.
Depression has significant co-morbidity with illnesses associated with hypovitaminosis D such as osteoporosis, diabetes, heart disease, hypertension, multiple sclerosis, and rheumatoid arthritis. Schizophrenia is associated with cardiac disease Davidson M. Risk of cardiovascular disease and sudden death in schizophrenia. J Clin Psychiatry. 2002;63 Suppl 9:5–11., diabetes (before the introduction of the atypical antipsychotics) Peet M. Diet, diabetes and schizophrenia: review and hypothesis. Br J Psychiatry Suppl. 2004 Apr;47:S102–5., osteoporosis Levine J, Belmaker RH. Osteoporosis and schizophrenia. Am J Psychiatry. 2006 Mar;163(3):549–50., and hypertension Smith M. APA: Schizophrenia Patients Go Untreated For Comorbidities. MedPage Today. 2006 May 24. —but not multiple sclerosis.
Vitamin D has a significant biochemistry in the brain.