There is strong epidemiological evidence that poor diet is associated with depression. The reverse has also been shown, namely that eating a healthy diet rich in fruit, vegetables, fish and lean meat, is associated with reduced risk of depression. To date, only one randomisedcontrolledtrial (RCT) has been conducted with elevated depressionsymptoms being an inclusion criterion, with results showing that a dietintervention can reduce clinical levels of depression. No such RCTs have been performed in youngadults.
Youngadults with elevated levels of depressionsymptoms and who habitually consume a poor diet were randomly allocated to a brief 3-week dietintervention (Diet Group) or a habitual diet control group (Control Group). The primary and secondary outcome measures assessed at baseline and after the intervention included 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).
Diet compliance was measured via self-report questionnaires and spectrophotometry. One-hundred-and-one individuals were enrolled in the study and randomly assigned to the Diet Group or the Control Group. Upon completion of the study, there was complete data for 38 individuals in each group. There was good compliance with the dietintervention recommendations assessed using self-report and spectrophotometry. The Diet group had significantly lower self-reported depressionsymptoms than the Control Group on the CESD-R (p = 0.007, Cohen's d = 0.65) and DASS-21 depression subscale (p = 0.002, Cohen's d = 0.75) controlling for baseline scores on these scales. Reduced DASS-21 depression subscale scores were maintained on follow up phone call 3 months later (p = .009).
These results are the first to show that youngadults with elevated depressionsymptoms can engage in and adhere to a dietintervention, and that this can reducesymptoms 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.
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