Citation: Ryu, S.-a.; Choi, Y.-J.; An, H.; Kwon, H.-J.; Ha, M.; Hong, Y.-C.; Hong, S.-J.; Hwang, H.-J. Associations between Dietary Intake and Attention Deficit Hyperactivity Disorder (ADHD) Scores by Repeated Measurements in School-Age Children. Nutrients 2022, 14, 2919. https://doi.org/10.3390/ nu14142919 Academic Editor: Joerg Koenigstorfer Received: 27 May 2022 Accepted: 15 July 2022 Published: 16 July 2022 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). nutrients Article Associations between Dietary Intake and Attention Deficit Hyperactivity Disorder (ADHD) Scores by Repeated Measurements in School-Age Children Su-a Ryu 1,† , Yean-Jung Choi 2,† , Hyojin An 1 , Ho-Jang Kwon 3 , Mina Ha 3 , Yun-Chul Hong 4 , Soo-Jong Hong 5 and Hyo-Jeong Hwang 2, * 1 Department of Food and Nutrition, Kyung Hee University, Seoul 02447, Korea; sua9336@naver.com (S.-a.R.); ddottori@naver.com (H.A.) 2 Department of Food and Nutrition, Sahmyook University, Seoul 01795, Korea; yjchoi@syu.ac.kr 3 Department of Preventive Medicine, Dankook University College of Medicine, Cheonan 31116, Korea; hojang@dankook.ac.kr (H.-J.K.); minaha@dankook.ac.kr (M.H.) 4 Department of Preventive Medicine, Seoul National University College of Medicine, Seoul 08826, Korea; ychong1@snu.ac.kr 5 Department of Pediatrics, Childhood Asthma Atopy Center, Humidifier Disinfectant Health Center, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea; sjhong@amc.seoul.kr * Correspondence: hjhwang@syu.ac.kr; Tel.: +82-2-3399-1653; Fax: +82-2-3399-1655 † These authors contributed equally to this work. Abstract: Attention deficit hyperactivity disorder (ADHD) is a common psychiatric disorder in school-age children and adolescents. However, the reported associations between ADHD and single nutrient intake are inconsistent. The aim of the study was to investigate the relationships between dietary intake changes and the prevalence of ADHD over time with repeat measurements using data from the Children Health and Environment Research (CHEER). To assess changes over time, we used data obtained in 2006 and 2008 (Phases 1 and 2 ). In this study, there were 2899 children aged 8 years or older in Phase 1 and 2120 children aged 9 years or older in Phase 2 from Korea, and the ADHD scores and dietary intake of 1733 children in Phases 1 and 2 were used in the final analysis. The YN group refers to children whose disease had improved in Phase 2 , and the NY group refers to children diagnosed with ADHD in Phase 2 . A notable within-group result was the increase in vegetable protein (p = 0.03) in the YN group. A between-group comparison showed that significant changes in nutrient intake could be confirmed most in the NY group, and the YN group tended to have a lower nutrient intake than the NY group. In the correlation of changes in nutrient intake and three subtypes (combined, AD, and HD), the total fat (p = 0.048) and animal protein (p = 0.099) showed a positive correlation with the prevalence of AD. Vegetable iron (p = 0.061 and p = 0.044, respectively), zinc (p = 0.022 and p = 0.007, respectively), vegetable protein (p = 0.074), and calcium (p = 0.057) had inhibitory effects on ADHD and its subtype. In conclusion, management of dietary and nutritional status should be considered to ameliorate ADHD and its subtypes in school-age children, and these relationships require further exploration in other settings. Keywords: dietary intake; mental health; children; attention deficit hyperactivity disorder; nutrients 1. Introduction Mental health is an important issue regardless of age, but children’s physical and mental states are particularly important, as they affect education and employment [1] and persist into adolescence and adulthood in a sizable majority of afflicted children [2]. Atten- tion deficit hyperactivity disorder (ADHD) is a common childhood psychiatric disorder found in school-age children and adolescents [3], and it has been recognized as a specific disease since the 1970s. It is classified into a type in which the attention deficit type is dominant, a type in which hyperactivity and impulsivity are dominant, and a complex type Nutrients 2022, 14, 2919. https://doi.org/10.3390/nu14142919 https://www.mdpi.com/journal/nutrients