In a study that focused on young men, switching to the Mediterranean diet was found to significantly improve symptoms of depression. Researchers were also surprised to see just how willing participants were to try out a new diet.

Depression is a common and still poorly understood condition that affects around 5% of adults worldwide — around 300 million people. Our ways of dealing with depression are still imperfect, and a team of scientists from the University of Technology Sydney wanted to see if dietary interventions can have an impact on depression symptoms (continuous low mood or sadness is one of the key symptoms of depression).

It’s not such a crazy idea as it sounds. Although depression is a clinical condition, a healthy diet has been found to improve mental state, which in turn has been found to have a positive impact on depression — something similar is true of exercise. Recent research has also found that the bacteria in our gut is linked to our mental health , and a good diet favors good gut bacteria.

“There are lots of reasons why scientifically we think food affects mood. For example, around 90% 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,” said Jessica Bayes, lead researcher of the new study. “To have beneficial microbes, we need to feed them fibre, which is found in legumes, fruits and vegetables,” she adds.

So the team embarked participants on a 12-week randomized control trial involving 72 participants to see whether switching to a Mediterranean diet, one of the healthiest types of diets, would have any positive effect.

“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.”

The main idea behind the Mediterranean diet is to eat less processed foods, sugar, and red meat, and eat more fruits, vegetables, and healthy grains. This type of food has been found to be beneficial for gut bacteria and has also been linked to better cardiovascular health and lower weight.

The results were positive and showed that a Mediterranean diet can help reduce depression symptoms, but researchers caution that the conclusions should not be extended to other demographics based on this work alone.

“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,” Bayes also says.

The team also emphasizes that nearly all participants stayed on the program, and many were keen to continue the diet even after the study ended.

This shows how “effective, tolerable and worthwhile they found the intervention,” Bayes concludes.