The association of dietary inflammatory index, functional foods and some antioxidants intake with COVID-19 vaccine side effects in Iranian adults

Abstract

Purpose This study aims to assess the association of dietary inflammatory index (DII), consumption of functional food and some antioxidants with COVID-19 vaccine side effects in Iranian adults. Design/methodology/approach This was a case–control study conducted among the 1,067 Iranian adults who were invited to participate through WhatsApp software. The dietary intake was assessed using the food frequency questionnaire. Findings There was a significant difference (p = 0.04) in vitamin D consumption between healthy people and persons with a vaccine side effect. Vitamin E intake in healthy participants was significantly (p = 0.04) more than case group. There was a significant difference in the consumption of zinc (p = 0.01), selenium (p = 0.02) and vitamin C (p = 0.02), between persons without vaccine side effects and the case group. Consumption of onion (82.5 ± 9.5 g/day vs 32.2 ± 6.3; p = 0.0001), garlic (6 ± 0.3 g/day vs 0.2 ± 0.08; p = 0.0001) and oat (2.2 ± 0.05 g/day vs 0.5 ± 0.01; p = 0.001) in the control group was significantly more than persons with vaccine side effects. With the increase in each unit in the score of the DII, the risk of COVID-19 vaccine side effect incidence increased 1.7 times (OR = 1.7; 95% CI: 1.3–1.8). Originality/value To the best of the authors’ knowledge, this study is the first that investigated the association between functional food intake and side effects of the COVID-19 vaccine.