Abstract: Objective To investigate the relationship between the composite dietary antioxidant index (CDAI) and cognitive function in children aged 6 to 11 years. 
Methods CADI was constructed based on the publicly available data from National Health and the Nutrition Examination Survey (NHANES Ⅲ) in the United States, as well as the data collected under a collaborative project with the University of Leeds in the United Kingdom titled "Food System Solutions for the Dual Burden of Malnutrition and Related Trace Nutrient Deficiency in Chinese Children" (referred to as Chinese data). Multiple Logistic regression was used to analyze the association between CDAI levels and cognitive function in children. Dietary surveys were conducted using 24-hour dietary regression and 24-hour dietary weighing methods. NHANES Ⅲ was analyzed using the Wide Range Achievement Test-Revised (WRAT-R) and the Wechsler Intelligence Scale for Children (WISC-R) of the Wechsler Intelligence Scale (WISC-R) test. The Chinese cognitive survey was analyzed using the Primary Cognitive Abilities Test (PCAT) and the perceptual reasoning (PR) of the WISC-R. 
Results A total of 470 Chinese children and 2 968 American children were included. Among Chinese survey respondents, there were 224 males, accounting for 47.70%, and 246 females, accounting for 52.30%. The survey respondents of NHANES Ⅲ included 1 494 males, accounting for 50.30%, and 1 474 females, accounting for 49.7%. After adjusting the covariates of gender, age, race, body mass index (BMI) and energy intake, CDAI was influencing factor of working memory (WM) of children aged 6  to 11 years (the China data: OR=1.04，95%CI： 1.00-1.20，P=0.047; The NHANES Ⅲ data: OR=1.13，95%CI： 1.01-1.28， P=0.038). The WM was significantly and positively associated with vitamin C and zinc intake in children aged 6 to 11 years (the China data: zinc P=0.009, vitamin C P=0.030; The NHANES Ⅲ data: Vitamin C P=0.040). 
Conclusion There is a significant correlation between CDAI and WM in children′s cognitive function, and among the components that make up CDAI, the role of zinc and vitamin C is more pronounced. The results of this study suggest that the development of WM in children can be promoted by increasing the intake of dietary antioxidant nutrients. 

Key words: composite dietary antioxidant index, cognition, children