Do Nutrient Supplements Have Any Effect on Mental Disorders? World's largest review of the evidence

From PsychCentral, 20/10/2019

A growing number of studies have examined the benefits of nutrient supplementation in people with mental disorders. But which supplements have been proven to work - and for which disorders?

Now, in the world’s largest review of this topic, an international team of scientists led by Australia’s National Institute of Complementary Medicine (NICM) examined the  best available evidence and narrowed it down to which specific nutrients can assist in the management of certain mental health disorders.

The findings are published online in the journal World Psychiatry.

The team examined 33 meta-analyses of randomized control trials and data from 10,951 people with mental health disorders including depression, stress and anxiety disorders, bipolar disorder, personality disorders, schizophrenia and attention-deficit/hyperactivity disorder (ADHD).

The aim was to provide a clear overview of the benefits of specific nutrient supplements - including dosage, target symptoms, safety and tolerability - across different mental disorders.

Although the majority of nutritional supplements assessed did not significantly improve mental health, the researchers found strong evidence that certain supplements are an effective additional treatment for some mental disorders, supportive of conventional treatment.

All nutrient supplements were found to be safe when recommended dosages and prescriptive instructions were adhered to and there was no evidence of serious adverse effects or contraindications with psychiatric medications.

Among the results:

• the strongest evidence was found for omega-3 supplements (a polyunsaturated fatty acid) as an add-on treatment for major depression. Omega-3 reduced symptoms of depression beyond the effects of antidepressants alone;

• there was some evidence to suggest that omega-3 supplements may also have small benefits for ADHD;

• there was emerging evidence for the amino acid N-acetylcysteine as a useful adjunctive treatment in mood disorders and schizophrenia;

• special types of folate supplements may be effective as add-on treatments for major depression and schizophrenia, however folic acid was ineffective;

• there was no strong evidence for omega-3 for schizophrenia or other mental health conditions;

• there is currently a lack of compelling scientific evidence supporting the use of vitamins (such as E, C, or D) and minerals (zinc and magnesium) for any mental disorder.

According to the researchers, the findings can be used to produce more evidence-based guidance on the usage of nutrient-based treatments for various mental health conditions.

“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,” said lead author Dr. Joseph Firth, Senior Research Fellow at NICM Health Research Institute, Western Sydney University and Honorary Research Fellow at The University of Manchester.

“In this most recent research, we have brought together the data from dozens and dozens of clinical trials conducted all over the world, in over 10,000 individuals treated for mental illness.”

“This mass of data has allowed us to investigate the benefits and safety of various different nutrients for mental health conditions, on a larger scale than what has ever been possible before.”

Senior author Professor Jerome Sarris of the NICM institute said as the role of nutrition in mental health is becoming increasingly acknowledged, it was vital that an evidence-based approach be adopted.

“Future research should aim to determine which individuals might benefit most from evidence-based supplements and to better understand the underlying mechanisms so we can adopt a targeted approach to supplement use in mental health treatment,” said Sarris.

“The role of the gut microbiome in mental health is a rapidly emerging field of research, however more research is needed into the role of ‘psychobiotics’ in mental health treatment.”