Abstract

Background: The Dietary Approach to Stop Hypertension (DASH) eating pattern has been recommended as a healthy dietary plan by several international guidelines. However, data on the association between the DASH diet and breast cancer is limited. This study investigated the association between the DASH dietary pattern and risk of breast cancer. Materials and Methods: This is a hospital-based case-control study conducted between 2014 and 2016 in the Cancer Institute of Iran. Patients with histopathologically confirmed breast cancer were recruited. Controls were healthy subjects who were frequency matched to cases by residential place and age (±10 years). A validated 168-item Food Frequency Questionnaire was applied to assess the dietary intake of participants. Physical activity was assessed using the Global Physical Activity Questionnaire. The DASH dietary pattern scores were calculated using the method introduced by Fung. Unconditional logistic regression, in which potential confounders were taken into account, was applied to determine the association between adherence to the DASH dietary pattern and odds of breast cancer. Results: The study participants comprised 477 patients with breast cancer and 507 healthy controls. In the total population, patients with breast cancer were slightly older (45.9 vs. 43.9 years, P = .02), had slightly higher BMI (21.9 vs. 20.2, P = .01) and were less physically active (20 vs. 27 MET h/wk. P < .01) than controls. In Model A, which was adjusted for age and energy intake, adherence to the DASH dietary pattern substantially reduced breast cancer risk in the total population (OR for comparing extreme tertiles: 0.62; 95 CI 0.44-0.78; Ptrend = 0.004). Even after controlling for more cofounders, greatest adherence to DASH diet was associated with a 34 reduction in risk of breast cancer (OR 0.66; 95 CI 0.46, 0.94; Ptrend = 0.03). In premenopausal women, adherence to the DASH dietary pattern was insignificantly associated with a 32 reduction in breast cancer risk. This risk reduction was 38 in postmenopausal women, which was also not found to be significant Conclusion: Adherence to the DASH dietary pattern could be associated with an approximately 30 reduction in risk of breast cancer. However, further studies, in particular studies with prospective design, are required to confirm this claim. © 2021