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Healthy diet improved depression symptoms in young adults

Eating less processed food and more fruit, vegetables, fish and olive oil improved depression symptoms

Louise Prime

Friday, 11 October 2019

Young adults with depression symptoms were able to comply with a healthy diet intervention and benefited from improvements in depression that were maintained three months after the intervention, a small study* has found. The authors said they had shown that a modest change to diet is a useful adjunct therapy to reduce symptoms of depression.

The research team, from Sydney, Australia, said in PLOS ONE that there is already strong epidemiological evidence that poor diet is associated with depression – and that eating a healthy diet rich in fruit, vegetables, fish and lean meat, is associated with reduced risk of depression. However, there has been only one randomised controlled trial (RCT) conducted with elevated depression symptoms being an inclusion criterion, with results showing that a diet intervention can reduce clinical levels of depression; and no such RCTs have been performed in young adults.

They randomised 17-35 year olds with moderate to high depression symptoms, and who habitually consumed a poor diet (high in processed foods, sugar, and saturated fats), to either a brief three-week diet intervention (diet group) or a habitual diet control group (control group). People in the diet change group watched a 13-minute video with instructions from a registered dietician to increase their intake of vegetables (five servings per day), fruits (2–3 per day), wholegrain cereals (three per day), protein (lean meat, poultry, eggs, tofu, legumes; three per day), unsweetened dairy (three per day), fish (three per week), nuts and seeds (three tablespoons per day), olive oil (two tablespoons per day), spices (turmeric and cinnamon; one teaspoon most days) – and to decrease refined carbohydrate, sugar, fatty or processed meats and soft-drinks. They were also given a small hamper of olive oil, natural nut butter, nuts and seeds (walnuts, almonds, pepitas, sunflower seeds) and spices (cinnamon, turmeric).

At baseline and after the intervention the researchers assessed several outcomes including symptoms of depression (Centre for Epidemiological Studies Depression Scale; CESD-R; and Depression Anxiety and Stress Scale-21 depression subscale; DASS-21-D), current mood (Profile of Mood States), self-efficacy (New General Self-Efficacy Scale) and memory (Hopkins Verbal Learning Test).

On completion of the study, there were complete data for 38 people in each group. The researchers reported that there was good compliance with the diet intervention recommendations, assessed using self-report and spectrophotometry – the diet change group showed a significant increase in consumption of the recommended foods from baseline to three weeks compared with the control group. Furthermore, the diet group had significantly lower self-reported depression symptoms compared with the control group on the CESD-R and DASS-21 depression subscale, controlling for baseline scores on these scales.

The study authors were able to contact 33 people for three-month follow-up; data collected at this point indicated that intervention effects were maintained for the diet change group.

They commented: “One of the most interesting findings is the fact that diet change was feasible in this population. As the participants were young adults and university undergraduate students, we [had] anticipated several potential barriers such as the perceived cost of the diet, the time demands of preparing food and/or reliance on others for food preparation (particularly if they lived at home).”

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

“These results are the first to show that young adults with elevated depression symptoms can engage in and adhere to a diet intervention, and that this can reduce symptoms of depression. The findings provide justification for future research into the duration of these benefits, the impacts of varying diet composition, and their biological basis.”

*Francis HM, Stevenson RJ, Chambers JR, et al. A brief diet intervention can reduce symptoms of depression in young adults - A randomised controlled trial. PLoS ONE 2019; 14(10): e0222768. DOI:10.1371/journal.pone.0222768

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