(Poly)phenol intake and mental health: a scoping review

Recent evidence suggests that dietary (poly)phenols may influence mental health through biological pathways. Although human studies have investigated the relationship between (poly)phenol consumption and mental health outcomes, the breadth and distribution of the evidence have not been comprehensively synthesized. This scoping review aimed to map human evidence on dietary (poly)phenol consumption and mental health outcomes, including depression, anxiety, stress, and mood, and to characterize the (poly)phenol classes, dietary sources, intervention approaches, study populations, and outcome measures investigated. PubMed/MEDLINE, Scopus, and the Cochrane Library were searched for observational and intervention studies in humans. Animal and in vitro studies were excluded. A total of 174 studies were included, comprising 11 observational and 163 intervention studies. Depression was the most frequently investigated outcome, followed by mood, anxiety, and stress. Most intervention studies evaluated purified or extracted (poly)phenols, particularly curcuminoids and isoflavones, whereas fewer investigated (poly)phenol-rich foods or dietary patterns. Berries, cocoa, soy products, and tea were the most studied food sources. Heterogeneity was observed across study populations, intervention characteristics, outcome measures, and methods used to assess (poly)phenol exposure. This review highlights the current evidence, identifies methodological and research gaps, and provides a foundation for future research, systematic reviews, and clinical studies.