BACKGROUND/OBJECTIVES: Depression and anxiety are common mental health problems.Anthocyanins from berries might have an inhibitory effect on monoamine oxidase (MAO) enzymes and alleviate various mood and anxiety symptoms. This study examined the effects of a daily supplement of an anthocyanin-rich product on mental health problems. SUBJECTS/METHODS: This study was a secondary analysis from a randomized, 6-week, open-label trial in 300 healthy participants aged 18–60 years who consumed 1 or 2 servings of anthocyanin-rich mulberry milk daily. The General Health Questionnaire-28 (GHQ-28) and Hospital Anxiety and Depression Scale (HADS) were used to monitor mental health problems. In addition, the saliva activity levels of MAO-A, MAO-B, and cortisol were examined at the baseline and after 6 weeks. RESULTS: The total scores of the GHQ-28 and HADS and all their subscales decreased in both groups (all P < 0.05). The cortisol, MAO-A, and MAO-B activities decreased significantly (all P <0.05), but there were no significant differences between the groups (all P > 0.05). Significant correlations were noted between the decreased activity level of MAO-A enzyme and decreased scores from the GHQ-28 somatic subscale and the HADS depression subscale (all P < 0.05). CONCLUSIONS Daily consumption of anthocyanin-rich mulberry milk possibly improves mental health problems by reducing depressive and anxiety symptoms in the working population. The suppression of MAO-A activity is a possible underlying mechanism.