Dietary total antioxidant capacity in relation to depression and anxiety in Iranian adults

•Overall, 28.6 % (n = 943) of study participants were depressed or at the borderline level.•Overall, 13.6 % (n = 448) of study participants had anxiety or were at the borderline level.•We found an inverse significant inverse association between dietary total antioxidant capacity and odds of depression among adults.•We found an inverse significant inverse association between dietary total antioxidant capacity and odds of anxiety among adults. Although several studies are available that link individual dietary antioxidants to the risk of psychological disorders, data about the association of dietary total antioxidant capacity (TAC) with depression and anxiety are scarce. This study was conducted to investigate the association between dietary TAC and odds of depression and anxiety among Iranian adults. In this cross-sectional study, the dietary intakes of 3297 apparently healthy adults in the Isfahan province of Iran were assessed using a validated food-frequency questionnaire. Dietary TAC was estimated using the ferric-reducing antioxidant power international databases. Depression and anxiety were assessed using a validated Persian translated version of the Hospital Anxiety and Depression Scale questionnaire. Scores of 0 to 7 in either subscales of the questionnaire were considered normal, and scores of ≥8 indicated the presence of depression or anxiety. Overall, 943 study participants (28.6%) were depressed, and 448 participants (13.6%) had anxiety. After controlling for potential confounders, including the dietary intake of omega-3 fatty acids, we found that participants in the top quintile of the dietary TAC were 43% less likely to be depressed than those in the bottom category (odds ratio: 0.57; 95% confidence interval, 0.40–0.82; Ptrend = .001). Regarding anxiety, we found an inverse significant association between dietary TAC and anxiety when comparing the extreme quintiles (odds ratio: 0.62; 95% confidence interval, 0.39–0.99; Ptrend = .06). We found an significant inverse association between dietary TAC and odds of depression and anxiety among adults. Further prospective studies are required to confirm these findings.