The body of evidence around how diet can influence our mental wellbeing continues to build as studies demonstrate the dangers of sustained unhealthy eating habits. New research has explored this phenomenon in young men suffering from clinical depression, and shown that switching to a healthier Mediterranean diet can bring about rapid and significant reductions in symptoms.

The research was carried out by scientists at the University of Technology Sydney and focused on mental health in young men. Depression is among the most commonly reported mental health disorders for this demographic and is a significant risk factor for suicide, with men making up more than three quarters of death by suicide in Australia, according to government figures.

The study involved 72 subjects aged 18 to 25 with moderate to severe depression and poor diets, who were randomly assigned to a group either shifting to a Mediterranean diet or undertaking a form of social support called befriending therapy, as a control.

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

Assessments were carried out at the start, midway and end of the 12-week trial with commonly used self-reporting scales for depression and quality of life. At the trial's conclusion, the Mediterranean diet group scored significantly higher on both fronts compared to the control group undertaking befriending therapy, indicating that the shift in diet had contributed to their mental wellbeing.

The findings add further weight to the idea that healthier eating habits can have a real impact on symptoms of depression, something we've seen explored through a number of interesting studies in recent years. One paper in 2018 showed that a diet designed to lower blood pressure could also lower rates of depression. Others have shown that Mediterranean-style diets can offer relief from depression, including over periods of just a few weeks.

One thing that is tricky to control for with such trials is the elimination of any potential placebo effect. Does simply knowing that we're eating more healthily confer its own benefits to our mental health? Its very difficult to rule out completely, but when viewed in the context of other research in this area the findings do further support the idea that diet can influence our mood.

Researchers are also making inroads when it comes to understanding the scientific basis for this relationship. Studies on gut bacteria continue to offer fascinating insights into how it shapes mental health, linking specific strains to increased rates of depression, and showing how altering the gut microbiome with antibiotics or fecal transplants can reduce depressive behaviors in mice.

"There are lots of reasons why scientifically we think food affects mood," said Bayes. "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. To have beneficial microbes, we need to feed them fiber, which is found in legumes, fruits and vegetables."

One of the benefits of a dietary change as a treatment for depression is the potential for higher adherence among patients. While traditional approaches such as cognitive behavioral therapy or anti-depressant medication don't prove effective for a large portion of people, the emerging idea of "nutritional psychiatry," where specific nutrients and eating habits are used as tools instead, could offer a viable alternative.

“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."

The research was published in The American Journal of Clinical Nutrition.

Source: University of Technology Sydney