Dietary Inflammatory Index and Odds of Breast Cancer in a Case-Control Study from Iran

Abstract

Chronic inflammation is implicated in breast cancer (BrCa) development; however, studies on the association of the inflammatory potential of diet and breast cancer have produced conflicting results. With this as background, we investigated the association between dietary inflammatory index (DII^®) scores and BrCa risk in an Iranian case-control study. In this study, 136 newly diagnosed breast cancer patients and 272 hospitalized controls were recruited using convenience sampling. DII scores were computed from dietary intake data collected through a validated food frequency questionnaire (FFQ). Adjusted odds ratios (OR) and 95% confidence intervals (CI) for the association between the DII and BrCa risk were estimated by logistic regression. After controlling for multiple potential confounders, a significantly increased BrCa odds was observed in the highest quartile of DII score compared to the lowest quartile (OR_{quartile 4 vs. 1} = 2.64, 95% CI: 1.12–6.25; P_trend = 0.01). In subanalysis based on menopausal status, a positive association was observed between the DII and BrCa risk among premenopausal women (OR_{quartile 4 vs. 1} = 5.51, 95% CI: 1.45–20.93; P_trend = 0.005); however, no association was detected in postmenopausal women. Our findings suggest that more proinflammatory diets, indicated by higher DII scores, may increase the odds of BrCa, especially among premenopausal women.

Acknowledgments

We are grateful to all field investigators, staff, and participants of this study. Special thanks should be given to Dr. Arezoo Rezazadeh for comments that greatly improved the manuscript.

Disclosure Statement

J. R. H. owns controlling interest in Connecting Health Innovations, LLC (CHI), a company planning to license the right to his invention of the dietary inflammatory index (DII) from the University of South Carolina in order to develop computer and smartphone applications for patient counseling and dietary intervention in clinical settings. N. S. is an employee of CHI. The subject matter of this article will have no direct bearing on the work of CHI, nor has any CHI-related activity exerted any influence on this project.

Additional information

Funding

This study was supported by a grant from National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran. N. Shivappa and J.R. Hebert were supported by grant number R44DK103377 from the United States National Institute of Diabetes and Digestive and Kidney Diseases. None of the funding organizations had any role in the design, analysis, or writing of this article.