The Certainty of the Evidence on Plant- vs Meat-Predominant Dietary Patterns and Depression: An Umbrella Review

Diets rich in plant foods are associated with reduced risk of depressive symptoms. However, previous studies have reported greater depressive symptomology in patients who follow a plant-predominant dietary pattern. Meta-analyses and systematic reviews of associations of plant- and meat-predominant diets and depression have highlighted conflicting results.

In this umbrella review we applied A Measurement Tool to Assess Systematic Reviews 2 (AMSTAR2) to explore the state of evidence regarding possible associations of plant- and meat-predominant dietary patterns with depression.

Six databases were searched from the date of inception to January 2025: CINAHL, MEDLINE, PsycINFO, Psychology and Behavioral Sciences Collection, Scopus, and Web of Science.

Data were extracted by 2 independent researchers using Covidence software.

The search revealed 104 studies, of which 9 met inclusion criteria. Data were synthesized and narratively grouped by plant-predominant and meat-predominant dietary patterns.

Five articles reported associations between plant- and meat-predominant dietary patterns and depression, 4 reported that plant-predominant dietary patterns increased depression, and 5 found conflicting or no associations. Similar systematic search terms, overlap of primary studies, and short timeframes between reviews raise concerns about the validity and scientific contribution of repeated systematic review of this topic. To address these concerns, we highlight the need for greater awareness of methodological issues, including high reliance on observational studies, high levels of heterogeneity, imprecision of measurement tools, and lack of measurement of dietary adherence and composition.