Study suggests healthy diet may directly reduce depression

Young adults with depression and an unhealth diet showed fewer symptoms of depression after eating a healthy diet for three weeks, according to a new study by researchers from Macquarie University in Sydney, Australia, and published in the journal PLOS One.

Heather Francis, PhD, lead author of the study, looked at 76 university students ages 17 to 35 years old exhibiting moderate-to-high depression symptoms and following a poor diet based on the Australian Guide to Healthy Eating, or a diet high in processed foods, sugar, and saturated fats.

Researchers randomized participants into a "diet change" group or a "regular diet" group. The diet change group was given brief instructions on improving their diet, as well as a healthy food hamper and $60 towards groceries. Each group member also received two subsequent phone check-ins. The regular diet group did not get any diet instructions and were asked to return after three weeks.

Before and after the intervention, the researchers assessed participants' scores for depression, anxiety and overall mood, and their performance on several learning and reasoning tasks.

At the end of the three weeks, the diet change group had successfully maintained a healthy diet and showed significant improvement in mood, with depression scores shifting into the normal range. The regular diet group's depression scores remained stable in the moderate to high range. The diet change group also showed significantly lower anxiety scores than the regular diet group, though other measures were not significantly different between the groups.

The authors followed up with 33 of the participants after three months. In this small sample, they found that, while only 21 percent of these participants fully maintained the healthy diet, those that did maintained their improvements in mood.

"Modifying diet to reduce processed food intake and increase consumption of fruit, vegetables, fish and olive oil improved depression symptoms in young adults,” said Francis in a statement. “These findings add to a growing literature showing a modest change to diet is a useful adjunct therapy to reduce symptoms of depression."