Joseph Firth, PhD, from Western Sydney University in Westmead, Australia, and colleagues conducted a systematic literature review to identify all meta-analyses of randomized controlled trials reporting on the efficacy and safety of nutrient supplements in common and severe mental disorders.
The researchers identified 33 meta-analyses of placebo-controlled randomized controlled trials that included outcome data on 10,951 individuals. Polyunsaturated fatty acids (PUFAs; particularly as eicosapentaenoic acid) showed the strongest benefit as an adjunctive treatment for depression.
PUFAs may have small benefits for attention-deficit/hyperactivity disorder, based on less advanced evidence, but there was no evidence of a benefit for schizophrenia. There was a wide amount of research on folate-based supplements as adjunctive treatments for depression and schizophrenia, and positive effects were seen with high-dose methylfolate for major depressive disorder. N-acetylcysteine might be useful as an adjunctive treatment in mood disorders and schizophrenia, but the evidence is emergent. There was no evidence supporting the use of vitamins and minerals for any mental disorder. There was no evidence of serious adverse effects or contraindications with psychiatric medications for any nutrient supplements.
“While there has been a longstanding interest in the use of nutrient supplements in the treatment of mental illness, the topic is often quite polarizing, and surrounded by either over-hyped claims or undue cynicism,” Firth said in a statement. “Clinicians should be informed of the nutrient supplements with established efficacy for certain conditions.”