Abstract: British Journal of Nutrition, page 1 of 9 © The Author(s), 2021. Published by Cambridge University Press on behalf of The Nutrition Society doi:10.1017/S0007114521003214 The relationship between Dietary Inflammatory Index and disease severity and inflammatory status: a case–control study of COVID-19 patients Jalal Moludi1,2,3, Shaimaa A. Qaisar4, Mohammad Alizadeh5*, Hamed Jafari Vayghan6, Mohammad Naemi5, Akram Rahimi3 and Rihaneh Mousavi5 1 Department of Nutritional Sciences, School of Nutritional Sciences and Food Technology, Kermanshah University of Medical Sciences, Kermanshah, Iran 2 Research Center for Environmental Determinants of Health (RCEDH), Kermanshah University of Medical Sciences, Kermanshah, Iran 3 Clinical Research Development Center, Imam Reza Hospital, Kermanshah University of Medical Sciences, Kermanshah, Iran 4 Chemistry Department, College of Education, University of Garmian, Sulimmania, Iraq 5 Nutrition Research Center, Faculty of Nutrition, Tabriz University of Medical Sciences, Tabriz, Iran 6 Department of Nutrition, School of Health, Arak University of Medical Sciences, Arak, Iran (Submitted 9 March 2021 – Final revision received 1 August 2021 – Accepted 18 August 2021) Abstract Numerous studies have revealed strong relationships between COVID-19 and inflammation. However, the imminent link between diet-related inflammation and the COVID-19 risk has not been addressed before. So, we explored the capability of the Energy-Adjusted Dietary Inflammatory Index (E-DII) to predict the inflammatory markers, incidence and severity of COVID-19. We conducted a case-control study consisting of 120 adults; they had been admitted for COVID-19 at hospital during June and July, 2020. The E-DII score was calculated based on the dietary intake, which was evaluated by a 138-item semi-quantitative food frequency questionnaire. Serum levels of inflammatory markers including the Erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and White blood cells (WBCs) differential were measured. Severity of disease was assessed by chest radiology criteria. Patients with the maximum pro-inflammatory energy adjusted E-DII score had 7·26 times greater odds of developing COVID-19, as compared to those in tertiles 1 (E-DII T3 v. E-DII T1: OR = 7·26; 95 % CI 2·64 to 9·94, P < 0·001). Also, a positive association between E-DII and C-reactive protein (CRP) was observed (BE-DII = 1·37, 95 % CI 0·72, 2·02), such that with each unit increase in E-E-DII, the CRP levels were increased by 1·37 units. Furthermore, a significant association was found between E-DII and the severity of disease (BE-DII = 0·03, 95 % CI 0·01, 0·06. 0·024). Patients consuming a diet with a higher pro-inflammatory potential were at a greater risk of COVID-19 occurrence; also, the severity of disease was elevated with a high score inflammatory diet. Key words: Dietary Inflammatory Index: Severity: Inflammation: COVID-19 The outbreak of the novel coronavirus disease, also named ‘COVID-19’, has led to a devastating pandemic, threatening all humans throughout the world.(1) Currently, the number of confirmed cases is rising very quickly globally; it is an immense threat to the public health.(2) Similar to the Middle East respiratory syndrome corona virus (MERS-CoV) and severe acute respiratory syndrome corona virus (SARS-CoV), COVID-19 is characterised by the lower respiratory infection, causing acute respiratory distress syndromes.(3) Typical clinical symptoms of the..