Association of dietary phytochemical index (DPI) with psychological disorders and serum levels of adropin and brain-derived neurotrophic factor in Iranian adults

Considering the contradictory findings of earlier studies in terms of association between dietary phytochemical index (DPI) and psychological disorders, this study evaluated relationship between DPI and psychological disorders (as primary outcome), regarding their association with two effective hormones in mental health including adropin and brain-derived neurotrophic factor (BDNF) values (as secondary outcomes), among Iranian adults. This cross-sectional study was performed on 533 adults (246 females). Dietary intakes were collected through a 168-item food frequency questionnaire; DPI was estimated as percentage of energy intake derived from phytochemical-rich foods. Symptoms of depression and anxiety were assessed using Persian version of the Hospital Anxiety and Depression Scale (HADS). Persian version of the General Health Questionnaire (GHQ) was utilized to assess levels of distress symptoms. Fasting blood samples were gathered to assess adropin and BDNF levels. Participants in highest tertile of DPI, versus lowest tertile, had significantly lower odds of depression (OR multi−adjusted = 0.43, 95%CI: 0.24–0.80), anxiety (OR multi−adjusted = 0.18, 95%CI: 0.05–0.68), and distress (OR multi−adjusted = 0.45, 95%CI: 0.28–0.74). Stratified analyses revealed significant reductions in distress odds among males (OR multi−adjusted = 0.43, 95%CI: 0.21–0.90). Also, reduction depression (OR multi−adjusted = 0.32, 95%CI: 0.16–0.67) and distress (OR multi−adjusted = 0.49, 95%CI: 0.27–0.88) odds were seen in participants with overweight/obesity and also, reduction anxiety odds among normal-weight subjects (OR multi−adjusted = 0.04, 95%CI: 0.01–0.67). No significant associations were seen between adropin and BDNF values either with DPI or psychological disorders. Individuals with higher dietary intake of phytochemicals had lower odds of depression, anxiety and distress. Adropin or BDNF values were not associated with DPI categories or having psychological disorders.