Association between Dietary Inflammatory Index (DII) and the Risk of Polycystic Ovary Syndrome: A Case-Control Study

Background: Polycystic ovary syndrome (PCOS) is an inflammation-related condition and a common metabolic disorder in women at fertility ages. The Dietary Inflammatory Index (DII) is a validated nutritional tool for estimating the inflammatory potential of the diet. It is assumed that a high DII score (indicating a predominantly inflammatory diet) has an association with higher odds of PCOS. The current study aimed to investigate the association between DII and PCOS risk in women.  Methods: This case-control study was conducted in 2019-2020 on 120 newly-diagnosed PCOS cases and 120 healthy controls aged 18-45 years in Khorramabad, Iran. DII was estimated based on a validated 168-item Food Frequency Questionnaire (FFQ). Results: The mean±SD of DII in PCOS patients was 0.40±2.09, while it was 0.45±1.92 in the control group (P<0.001). There was a positive association between increasing DII score and the risk of PCOS (odds ratio= 2.41; 95%CI: 1.15-5.02, P for trend =0.006) in the crude model as the fourth quartile was compared with the lowest one. This association was still significant in several models after adjusting for age and energy intake (P for trend <0.001), in the model adjusted for the physical activity level, education status, and family history of PCOS (P for trend=0.003), and also after additional adjustment for BMI (P for trend= 0.003). Conclusions: The present study revealed that consuming more pro-inflammatory diets with higher DII scores is related to an increased risk of PCOS.