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. Nuclear receptors for vitamin D exist in the brain and vitamin D is involved in the biosynthesis of neurotrophic factors, synthesis of nitric oxide synthase, and increased glutathione levels—all suggesting an important role for vitamin D in brain function. Animal data indicates that tyrosine hydroxylase, the rate-limiting enzyme for all the brain's monoamines, is increased by vitamin D. Rats born to severely vitamin D deficient dams have profound brain abnormalities.
We found only three small studies in which vitamin D was given to improve mood, but two found a positive effect. The negative study used homeopathic doses (low doses) of vitamin D2 ergocalciferol.
Finally we briefly review toxicity and suggest treatment. Fear of vitamin D toxicity is unwarranted but rampant in the medical profession. Because vitamin D deficiencies are so widespread in the western world, psychiatrists should suspect the deficiency—especially in blacks, the aged, and those who avoid the sun. Serum 25(OH)D levels should be obtained when deficiency is suspected. Judicial exposure to sunlight, oral vitamin D, or both, aimed at restoring circulating levels of 25(OH)D between 35–55 ng/mL, is the treatment of choice for vitamin D deficiency in mentally ill patients. Cholecalciferol is the preferred oral preparation of vitamin D.