Sydney, Jun 4 (IANS): Young men with a poor diet saw a significant improvement in their symptoms of depression when they switched to a healthy Mediterranean diet, a new study has shown.

Mediterranean diet, which consists of fresh fruit, vegetables, fish, and grains, caused significant impact on young men's mental health.

According to researchers from the University of Technology Sydney, the study is the first randomised clinical trial to assess the impact of a Mediterranean diet on the symptoms of depression in young men aged 18-25.

The team conducted a 12-week randomised control trial, where the men were asked to switch to foods rich in colourful vegetables, legumes and wholegrains, oily fish, olive oil and raw, unsalted nuts from their regular as well as fast foods.

The findings, published in the peer-reviewed American Journal of Clinical Nutrition, suggested that doctors should recommend patients to a nutritionist or dietician as part of their treatment plan, the researchers said.

"The primary focus was on increasing diet quality with fresh wholefoods while reducing the intake of 'fast' foods, sugar and processed red meat," said researcher Jessica Bayes, a candidate in the UTS Faculty of Health.

"There are lots of reasons why scientifically we think food affects mood. For example, around 90 per cent of serotonin, a chemical that helps us feel happy, is made in our gut by our gut microbes.

"There is emerging evidence that these microbes can communicate to the brain via the vagus nerve, in what is called the gut-brain axis," Bayes said.

"The results showed that nearly all our participants stayed with the programme, and many were keen to continue the diet once the study ended, which shows how effective, tolerable and worthwhile they found the intervention," the researchers said.

The study "suggests that medical doctors and psychologists should consider referring depressed young men to a nutritionist or dietitian as an important component of treating clinical depression", she said.