Food-based Dietary Inflammatory Index Trend and Dietary Inflammatory Index Determinants for the Period (1991–2021) in Iran

Background: Chronic systemic inflammation is a contributing factor to many chronic diseases. Diet affects the development and prevention of diseases. Moreover, Food-based Dietary Inflammatory Index (FDII) provides a classification for foods that scores a person's diet. Therefore, the aim of the present study is to provide an overall picture of the changes in the FDII in Iran, as well as factors associated with these changes, over the past three decades. Methods: This is a cross-sectional study. The Iranian Statistics Center (ISC) provided the purchase data obtained from the annual Household Income and Expenditure Survey. FDII was calculated based on 15 food groups (seven anti-inflammatory and eight pro-inflammatory). The authors plotted the inflammatory profile for the 30 years (1991–2021) to observe the changes in DII over different years. Results: This study showed there is an increased percentage of Iranians who currently consume a pro-inflammatory diet compared to three decades ago. Furthermore, FDII showed a higher anti-inflammatory food consumption rate as the age of the household head increased (r=0.68, P<0.001). Conversely, FDII indicated a higher inflammatory food consumption rate as the socioeconomic status score increased (r=-0.06, P<0.001). Thus, the authors observed a direct association between the total energy intake from the diet and the consumption of pro-inflammatory foods (r=0.11, P<0.001). Conclusion: This study revealed a strong association between the dietary inflammatory profile and recent dietary trends. The authors recommend calculating and plotting the trend of the dietary inflammatory profile for micronutrients for future studies.