Polyphenols, a diverse group of naturally occurring compounds found in plant foods such as fruits, vegetables, tea, and cocoa, have been investigated for their potential antidepressant effects. The scientific rationale for their use in supporting or treating depression is based primarily on their antioxidant, anti-inflammatory, and neuroprotective properties. Several preclinical studies suggest that polyphenols can modulate neurotransmitter systems, reduce neuroinflammation, and enhance neurogenesis, all of which are implicated in the pathophysiology of depression.

Human evidence, however, remains limited and inconsistent. Some small clinical trials and observational studies have reported modest benefits of polyphenol-rich foods (such as dark chocolate or green tea) or supplements (such as curcumin, resveratrol, or flavonoids) on mood and depressive symptoms. Meta-analyses indicate that certain polyphenols may exert small, statistically significant effects on depressive symptoms, but these findings are not robust and often limited by study design, sample size, and heterogeneity in polyphenol types and dosages.

In summary, while there is a plausible scientific basis and some emerging clinical evidence suggesting polyphenols may help alleviate depressive symptoms, the overall quality and consistency of the evidence are moderate at best. More large-scale, high-quality clinical trials are needed to confirm efficacy and clarify which polyphenols, doses, and populations might benefit most.