Relationship between breast cancer and dietary inflammatory index; a case–control study

Breast cancer is the leading cause of cancer–related mortality among women around the world. The relationship between the inflammatory potential of diet and breast cancer has been studied extensively, but results remain inconsistent. This study aimed to investigate the association between the dietary inflammatory index (DII) and odds of breast cancer. This case–control study includes 180 women with breast cancer and 360 healthy women randomly selected from those referred to Shohadaye Tajrish hospital in Tehran, Iran. The DII scores were computed based on a 168-item food frequency questionnaire (FFQ) assessed based on dietary intake. After adjusting the potential confounders, logistic regression models were used to estimate multivariable odds ratios (ORs). The positive association was found between DII and breast cancer risk. A higher level of DII was associated with a higher risk of developing breast cancer after being adjusted for age (OR: 2.11, 95% CI: 1.01–4.46, P = 0.04). Additional adjustments for BMI, alcohol consumption, smoking, pregnancy number, abortion number, breastfeeding duration, menopause age, and total calorie intake did not change the results (OR: 5.02, 95% CI: 1.43–17.58, P = 0.01). Following a pro-inflammatory diet was associated with an increased risk of BC. Further longitudinal studies are warranted.