Diversity of dietary (poly)phenols is associated with mental health independently of total (poly)phenol intake in young adults

Higher dietary (poly)phenol intake has been linked with better mental health, but whether consuming a greater diversity of dietary (poly)phenols provides additional benefits beyond total intake remains unknown. Here, we examined associations between dietary (poly)phenol diversity, total (poly)phenol intake and mental health in 307 healthy young adults, by combining complementary dietary assessments with objective measures of (poly)phenol exposure, gut microbiome profiling and salivary cortisol measurements. Greater dietary (poly)phenol diversity was independently associated with lower anxiety, perceived stress and mood disturbance after adjustment for total (poly)phenol intake and lifestyle factors. Higher total (poly)phenol intake was also independently associated with lower perceived stress and mood disturbance, as well as greater gut microbial diversity and differences in microbial composition. These findings suggest that both the quantity and diversity of dietary (poly)phenols capture complementary aspects of dietary exposure and should be considered when evaluating relationships between dietary (poly)phenols and mental health.