The association between the Index of Nutritional Quality (INQ) and breast cancer and the evaluation of nutrient intake of breast cancer patients: A case-control study

Objective: Breast cancer (BrCa) is the most frequently diagnosed cancer among females and second cancer after lung cancer in many societies. In Iran, the risk for BrCa is 1 in 35 and each year, 8000 new patients have been diagnosed with BrCa. Studies have shown that dietary components are implicated in the etiology of BrCa. The Index of Nutritional Quality (INQ) is a method of quantitative and qualitative analysis of single foods, meals, and diets. The aim of this study was to determine the usefulness of INQs in predicting BrCa risk. Methods: Our case-control study was conducted from March 2015 to February 2016. The study included 145 cases and 148 controls who attended the Shahid Beheshti University of Medical Sciences Cancer Research Center. INQ scores were computed based on dietary intake using a validated 168-item food frequency questionnaire. Logistic regression models were used to estimate multivariable odds ratios adjusted body mass index, education, employment, marital status, menarche age, childbirth number, smoking, menopause status, and physical activity. Results: Vitamins A, C, B₁, B₂, and B₁₂ and selenium INQs as a continuous variable in relation to risk for BrCa showed a significant association after multivariate adjustment (odds ratio [OR]_vitA, 0.41 [0.27–0.64]; OR_vitC, 0.30 [0.20–0.47]; OR_vitB1, 0.08 [0.04–0.17]; OR_vitB2, 0.19 [0.11–0.34]; OR_vitB12, 0.44 [0.31–0.61]; and OR_selenium, 0.42 [0.26–0.67]). Conclusion: Women who consumed a healthier diet including vitamin A, β-carotene, vitamin C, and folate and low-fat milk were at decreased risk for developing BrCa compared with those whose diet included more high fat and lamb meat.