Polyphenol Consumption and Its Association with Physical and Mental Health in Adults with Major Depressive Disorder

<b>Background/Objectives</b>: Research confirms that diet can influence the onset or course of depression. Polyphenols are bioactive plant compounds with proven beneficial effects on health. The aim of this study was to assess the relationship between polyphenol intake and the health status of individuals with major depressive disorder (MDD). <b>Methods</b>: The study included 44 participants. Health status was assessed using questionnaires adapted into Polish, body composition analysis, and laboratory blood tests. Polyphenol intake was estimated using the Phenol-Explorer program. <b>Results</b>: Among men, polyphenol intake was positively associated with glycated hemoglobin levels (R = 0.70; <i>p</i> = 0.038). Lower polyphenol intake in women was associated with poorer physical health (<i>p</i> = 0.014) and overall quality of life (<i>p</i> = 0.013). Polyphenol intake enhanced the effects of visceral fat content, muscle mass, severity of depressive symptoms (positive), and severity of stress symptoms (negative) on triglyceride levels. Polyphenol intake was positively associated with LDL cholesterol levels, and this relationship was attenuated by body water and fat content. Polyphenol intake weakened the relationship between fat content (negative) and quality of life (positive) with cortisol levels (R² = 0.61; <i>p</i> < 0.001). <b>Conclusions</b>: Polyphenols act both directly and mediate the effects of other factors on the health status of individuals with MDD. Despite their proven beneficial effects, further research is needed to explore their potential impact and mechanisms of action in patients with MDD.