Eating a healthy diet rich in fruits, vegetables, fish, and lean meat is associated with a reduced risk of depression, according to a study.
The research, published in the journal PLOS ONE, found that young adults with depression whose diet is usually unhealthy showed significantly fewer symptoms of depression after eating a healthy diet for three weeks.
Researchers from Macquarie University in Australia, and colleagues studied 76 university students aged between 17 and 35 years.
They exhibited moderate-to-high depression symptoms and followed a poor diet based on the Australian Guide to Healthy Eating -- high in processed foods, sugar, and saturated fats.
The researchers randomised 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 dollars towards future groceries.
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Each group member also received two subsequent check-ins via phone call.
The regular diet group did not get any diet instructions and was simply asked to return after the three weeks were up.
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 researchers followed up with 33 of the participants after three months.
In this small sample, they found that while only 21 per cent of these participants fully maintained the healthy diet, those that did maintained their improvements in mood.
The researchers noted that the findings are derived from a small, specific population of university students.
However, they provide preliminary evidence that relatively small, simple diet adjustments can directly improve depression symptoms, and that these effects can last up to three months.