Behavioral interventions of dietary changes to reduce depressive symptoms: a meta-analysis

Aim: Many meta-studies have found that dietary interventions, particularly focusing on an anti-inflammatory diet, are effective for depressive symptom reduction. However, those interventions use a pre-planned controlled diet, thus limiting the real-life application of the findings. Some interventions combine behavioral support with a dietary intervention to help participants change their own diet without external restrictions. This meta-study examined the effect of those behavioral interventions on depressive symptoms. Methods: A systematic literature search was performed by searching relevant studies in databases, including PsycINFO, Medline, and PubMed, published by March 2021. Random effect models were used to combine the effect sizes. Subgroup analyses by type of intervention were also performed. Results: Seven studies, with a total of 773 participants at baseline, were eligible for the review. The effect size of depressive symptom score changes for intervention groups was significant with a medium effect size (r =.43, p <.01), and the effect size for the control groups was not significant. For the sub-group analyses, motivational interviewing interventions had a large effect size. Conclusion: These results confirm that behavioral interventions for dietary change are effective in improving depressive symptoms, especially with a motivational interviewing approach. Thus, integrating a dietary intervention into traditional depression treatment may help treat people with depression.