“Magnesium has traditionally been promoted as for muscular relaxation,” he said. “There has been some commentary about it as an anxiety-reducing agent but this is mainly based off animal study research … in terms of its use for improving mood, the evidence [also] isn’t strong.”
The strongest evidence for using supplements in mental health treatment was found for omega-3 tablets in treating depression. When used in conjunction with antidepressants, omega-3 was shown to reduce symptoms of depression further than medication alone.
However, while there was some evidence to indicate omega-3 may have small benefits in managing symptoms of ADHD, the review did not find the supplement was useful in treating schizophrenia or other mental health conditions.
There was also evidence that folate supplements may be effective as add-on treatments for major depression and schizophrenia.
“A good, balanced, quality wholefood diet is always the way to go,” said Professor Sarris, noting people can increase their omega-3 intake through foods such as fish and cooking oil. “But, that being said, there are certain nutrients as supplements, or ‘nutriceuticals’, which cannot be found in the diet.”
The review found emerging evidence for one of these “nutriceuticals”, N-acetylcysteine, as a useful add-on treatment in mood disorders and schizophrenia, although further study is needed. There was weaker evidence supporting the use of probiotics alongside traditional treatment for depression.
“While there has been a longstanding interest in the use of nutrient supplements in the treatment of mental illness, the topic is often quite polarising, and surrounded by either over-hyped claims or undue cynicism,” said lead author Dr Joseph Firth, who is the recipient of an academic fellowship funded by supplements brand Blackmores.
Professor Ian Hickie, co-director of health and policy at The University of Sydney’s Brain and Mind Centre, said it was important to stress the findings related to supplements used in addition to standard treatments in “seriously unwell” populations, and not on their own or in people with minor mental health issues. He said the strongest evidence for nutritional supplements in assisting the treatment of mental disorders was in omega-3, folate and N-acetylcsteine, as was reflected by the review.
“They’re the ones that people have consistently found small but significant evidence [for],” he said. “After that, everything falls off rather rapidly.”
However, Professor Hickie, who worked on some of the trials analysed by the NICM researchers although was not involved in the review, said the role of supplements as an additional treatment is rarely how people want to use them, or how they are marketed.
“What many people are looking for is alternatives to standard treatments, not ‘add ons’ … and these [supplements] are marketed to people through anecdotes, not clinical trials.”
Mary Ward is Deputy Lifestyle Editor of The Sydney Morning Herald and The Age.