A Mediterranean diet, high in fruits, vegetables, and legumes and low in processed foods, red meat, and sugar, was found to significantly reduce symptoms of depression in young men. Overall, the diet led to a reduction of 20.6 points on the depression scale thanks to the diet shift.

Depression is a common mental health disorder that affects about 350 million people worldwide. In Australia, where the study was carried out, about one million adults experience depression in any given year. Depression can present differently in each individual and can trigger a number of different symptoms; in general, however, it includes feelings of unhappiness and loneliness, hopelessness, and low self-esteem. Depression can also have physical symptoms and can alter cognitive function.

Standard treatment of major depressive disorder includes psychotherapies such as cognitive-behavioral therapy and anti-depressant medications. However, roughly 30% of patients fail to adequately respond to such medications and the effectiveness of antidepressants, in general, is hotly debated. Recently, researchers have started looking at the effect of lifestyle changes (especially dietary patterns), to see what effect they can have on patients’ mental health.

The diet with the most evidence of having a positive effect on depressive symptoms is the Mediterranean diet. While observational evidence shows following a Mediterranean diet can reduce the risk of developing depression, only a few experimental trials have been done and they have all focused on older adults.

With this in mind, researchers at the University of Technology Sidney in Australia wanted to determine if nutritional counseling could improve the diet quality, depressive symptoms, and overall quality of life of young adults with depression. This turned out to be the case.

“The primary focus was increasing diet quality with fresh whole foods while reducing the intake of ‘fast’ foods,” lead researcher Jessica Bayes said in a statement. “Medical doctors and psychologists should consider referring depressed young men to a nutritionist or dietitian as an important component of treating clinical depression.”

Diets and depression

Study participants were recruited from Australia over an 18-month period. They were randomized to receive either dietary support or befriending. Participants in both groups did assessments at the start of the study, in the middle (week six), and at program completion, which the researchers used to reach overall conclusions.

The group shifting to the Mediterranean diet experienced a mean reduction of 20.6 points on the depression scale at the end of the study. The researchers also found that 36% of the participants shifting diets reported low to minimal depressive symptoms. Improvements to the physical quality of life were also reported in the same group.

“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,” Bayes said in a statement.

While the results are promising, the researchers warned that dietary change usually comes with many challenges, and compliance over the long term poses significant difficulties. For example, previous studies have shown that men rate healthy behaviors as less important than women, leading to difficulties in engaging them in dietary shifts. In addition, for people experiencing severe depression symptoms, adhering to a specific diet can be a daunting and very difficult task, and any such interventions will require careful planning.

The study was published in the American Journal of Clinical Nutrition.

If you are experiencing feelings of depression, please contact your national health service and/or seek a helpline.