Experts at Deakin University said they might have found the diet that can help severely depressed people.
In a study published in the international journal BMC Medicine, researchers placed dozens of patients with major depressive disorders on a Mediterranean-style diet.
Researchers said one third of the participants reported a significant improvement in their mood and symptoms after 12 weeks of healthy eating.
"We already know that diet has a very potent impact on the biological aspects of our body that affect depression risks," Professor Felice Jacka, director of Deakin University's Food and Mood Centre said in a statement.
She added, the Mediterranean diet had been credited with improving cardiovascular health, reducing the risk of diabetes and increasing longevity.
"The immune system, brain plasticity, and gut microbiota seem to be central not just to our physical health, but also our mental health."
"And diet, of course, is the main factor that affects the gut microbiota."
For the study, Professor Jacka randomly selected 31 participants, and asked them to fully acquire the Mediterranean diet. They were also asked to reduce their intake of sweets, refined cereals, fried food and sugary drinks.
As part of social support, 25 participants received weekly visits from researchers. However, only 8 per cent of those in the social support group showed improvement in their symptoms.
Sarah Keeble, one of the participants who changed her diet, said the program was life changing.
"I felt clearer in my mind. I felt balanced. I felt happier. I actually had a lot more energy. I felt I could really kick this in the butt," she said in an interview.
"It's not going to cure depression, but you can certainly handle it very well."
Ms Keeble has continued the Mediterranean diet after finishing the program.
"I got so motivated because I felt so much better, better than I had in so long," she said.
"I'd like to help people in this situation where they think there's no hope."