Dietary quality index and the risk of breast cancer: a case-control study

BACKGROUND: Diet quality is a significant determinant in the etiology of breast cancer (BrCa), but further studies are required to explore this relationship. Therefore, we tried to assess if diet quality, assessed using the Diet Quality Index-International (DQI-I), was related to BrCa among the Iranian population. METHODS: In the present case-control research, 134 women with a recent diagnosis of BrCa and 267 without BrCa were selected as case and control groups. Individual food intake data from a food frequency questionnaire was used to compute DQI-I. Also, the multivariable logistic regression models were utilized to evaluate the association between DQI-I and BrCa odds . RESULTS: We found a significant association between the last tertile of DQI-I and BrCa odds in the fully adjusted model (odds ratio (OR) = 0.30; 95% confidence interval (CI): 0.15–0.56). The subgroup analysis based on menopausal status also showed a significant decrease in BrCa odds in pre-and post-menopausal women (pre-menopausal: OR = 0.27; 95% CI: 0.10–0.70 – post-menopausal status: OR = 0.35; 95% CI: 0.13–0.92). CONCLUSIONS: Our findings indicated that a higher DQI-I score was related to a lower chance of BrCa. According to our research, a healthy diet pattern is crucial for BrCa prevention. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12905-023-02588-6.