Three weeks is all it takes for dietary changes to reduce the symptoms of depression, a study in Australia has found. Young adults with depression whose diets contained high amounts of processed foods, sugar and fats, exhibited significantly fewer signs of depression after 21 days of consuming more fruit, vegetables, fish and lean meats.


Heather Francis and her colleagues at Macquarie University in Sydney, Australia, studied 76 students aged 17-35 with poor diets who exhibited moderate to high symptoms of depression.

The students were randomly split into 2 groups: one in which the students continued with their existing diets and another that received advice on healthy eating, a hamper of healthy foods and AU$60 (approx. £33) towards groceries.

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The researchers assessed each student for depression, anxiety and overall mood before and after the three-week test period, and also rated their performance on several learning and reasoning tasks.

At the end of the 3 weeks, the healthy eating group showed significant improvement in mood, with depression scores dropping into the normal range. Scores for the students who stuck to eating unhealthily remained in the moderate-to-high range.

What is depression?

Depression is a condition that affects your mental health. People who suffer from depression may experience intense feelings of hopelessness, anxiety and negativity for an extended period of time. Depression can present itself forms such as seasonal depression and persistent depressive disorder.

Symptoms include sleeping problems, difficulty concentrating, fatigue, changes in appetite and suicidal thoughts. Medical treatment includes antidepressants such as Selective Serotonin reuptake inhibitors, while cognitive behavioural therapy (CBT) can be an alternative to drugs.

The healthy diet group also showed significantly lower anxiety scores than the unhealthy diet group, though other measures were not significantly different between the groups.

The researchers checked in with 33 of the students 3 months after the test and found that while only 21 per cent of them stuck with the healthy diet, those that did managed to maintain 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,” say the study’s authors. “These findings add to a growing literature showing a modest change to diet is a useful adjunct therapy to reduce symptoms of depression.”

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Before going freelance, Rob spent almost four years on staff at BBC Science Focus magazine subediting news, features and reviews. He's now a freelance journalist and has written about everything from electric cars to decomposing bodies… although space and speed are what fascinate him most.