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Effects of Vitamins, Fatty Acids, Minerals, and Other Dietary Supplements on Schizophrenic Symptoms in People with Schizophrenia

Report from Norwegian Knowledge Centre for the Health Services (NOKC) No. 19-2011


November 2011

There is considerable scientific disagreement about the possible effects of dietary supplements on mental health and illness. Do dietary supplements (possibly in megadoses) have an effect on symptoms and consequences of schizophrenia?

We critically appraised randomized controlled trials about supplemental vitamins, fatty acids and other dietary supplements given to people diagnosed with schizophrenia. The primary outcome was symptoms of schizophrenia.

We evaluated the evidence to be of low or very low quality. It is therefore difficult to draw strong conclusions about the effects of vitamins, minerals and other dietary supplements on symptoms of schizophrenia. The evidence shows the following:

  • Vitamin C and the fatty acid EPA may have a beneficial effect on schizophrenic symptoms (low quality evidence)
  • Vitamin B6 and the fatty acid DHA may have no effect on schizophrenic symptoms (low quality evidence)
  • We are uncertain of the effect of the fatty acid GLA and of vitamin E on schizophrenic symptoms (very low quality evidence)
  • No studies about minerals fulfilled our inclusion criteria

Patients in most studies had few symptoms as a result of using antipsychotic medications. It was, thus, not much room for improvement, and this could have caused an underestimation of the effects of dietary supplements. The risk of adverse effects from the supplements is uncertain. Some adverse effects have been reported, but we could not tell whether the adverse effects were caused by the supplements.

No evidence of effect does not imply evidence of no effect. The included studies did not provide the highly individualized and long-term treatment regimens typically provided by orthomolecular medicine.

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Copyright ©2015 by The Norwegian Institute of Public Health (NIPH). All content is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International license (CC BY-NC-ND).
Bookshelf ID: NBK390594, PMID: 28510394, ISBN: 978-82-8121-431-6, ISSN: 1890-1298


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