“We were surprised by how willing the young men were to take on a new diet,” Bayes said. “Those assigned to the Mediterranean diet were able to significantly change their original diets, under the guidance of a nutritionist, over a short time frame.”

“It 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.

The study contributes to the emerging field of nutritional psychiatry, which aims to explore the effect that specific nutrients, foods and dietary patterns can have on mental health.

The diet used in the study was rich in colorful vegetables, legumes and whole grains, oily fish, olive oil and raw, unsalted nuts.

“The primary focus was on increasing diet quality with fresh whole foods while reducing the intake of ‘fast’ foods, sugar and processed red meat,” Bayes said.

“There are lots of reasons why scientifically we think food affects mood. For example,

around 90 percent 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.

“To have beneficial microbes, we need to feed them fiber, which is found in legumes, fruits and vegetables,” she said.

Roughly 30 percent of depressed patients fail to adequately respond to standard treatments for a major depressive disorder such as cognitive behavior therapy and anti-depressant medications.

“Nearly all our participants stayed with the program, and many were keen to continue the diet once the study ended, which shows how effective, tolerable and worthwhile they found the intervention.”

Source: Eurekalert