People with mental illness made "remarkable" improvements by taking a daily dose of nutritional supplements rather than conventional medicines, a trial has found.
The work by a Canterbury University clinical psychologist has shown the potential that consumption of the right micronutrients, such as vitamins, minerals and amino acids, could have for helping a range of mental health problems.
Many who took part in a trial with Associate Professor Julia Rucklidge showed improvements they had not shown under prescription drugs.
Dr Rucklidge said it should come as no surprise that micronutrients could affect psychiatric symptoms, as they were essential for the inner workings of the brain.
"It is possible that some individuals with mental illness either have deficiencies in nutrients or may need more for optimal brain functioning."
Dr Rucklidge's trial focused on sufferers of attention deficit hyperactivity disorder (ADHD), which affects 3 to 5 per cent of adults.
In the trial, 14 adults with both ADHD and severe mood dysregulation (SMD) took a 36-ingredient micronutrient formula that consisted of mainly vitamins, minerals and amino acids, over eight weeks.
Significant improvements were found on measures of inattention, hyperactivity and impulsiveness, mood, quality of life, anxiety and stress.
"Most of the individuals were in a moderate to severe depressed state at the start of the trial," Dr Rucklidge said..
"At the end of the eight weeks, the mean score on the depression measure fell in the normal non-depressed range, which is a fairly remarkable change in such a short time, especially as many had not experienced such improvements with other conventional treatments.
"Participants were monitored for a further two months and people who stayed on the micronutrient formula showed further improvements and the ones who came off showed regression in their symptoms."
Dr Rucklidge said another important finding of her work was that micronutrient treatment had few side effects in comparison to many of the mood stabilisers and stimulants used in conventional treatments.
Dr Lyndy Matthews, of the College of Psychiatrists, said there was a lack of scientific evidence to show micronutrients were an effective treatment for mental illness.
But she considered it very important for people being treated for mental illness to take care of their physical health, often directing her own patients to see a dietician.
The Mental Health Foundation welcomed another approach that could help treat mental illness, "particularly one that is more than just pharmaceutical products, and that people can work with themselves".
Drug treatments for mental illness, year ended June 2009
* Prescriptions for antipsychotic drugs: About 390,000
* Prescriptions for antidepressant drugs: About 1.23 million