Dietary phytochemical index and psychological disorders in a large sample of Iranian adults: a population-based study

Background: Intake of plant foods and phytochemicals can decrease the odds of mental health.

Aim: The aim of study is to investigate the association between Dietary Phytochemical Index (DPI) with symptoms of depression, anxiety and stress in a large sample of Iranian adults.

Methods: In this cross-sectional study, a total of 7385 adults aged 20-50 years old were provided from the recruitment phase of Yazd Health Study, a population-based cohort research on Iranian adults. Food intakes were assessed via a validated and reliable food frequency questionnaire. Symptoms of depression, anxiety and stress were assessed using a validated Depression, Anxiety and Stress Scales questionnaire with 21-items. DPI was calculated by the percent of daily energy intake taken from phytochemical-rich foods.

Results: After adjustment for potential confounders, normal weight subjects in the highest tertile of DPI had lower odds of depression (OR 0.65; 95% CI 0.44-0.97) and anxiety symptoms (OR 0.65; 95% CI 0.45-0.93) compared with those in the lowest tertile. However, the apparent association was not found between depression, anxiety and stress in overweight and obese subjects.

Conclusion: We found a significant association between DPI and mental health in normal weight adults. Prospective studies are required to approve these conclusions.