Kozyra Magdalena, Zimnicki Patryk, Kaczerska Justyna, Śmiech Natalia, Nowińska Martyna, Milanowska Joanna. Relationship between the diet and psychiatric diseases such as depression, anxiety and attention-deficit hyperactivity disorder (ADHD). Journal of Education, Health and Sport. 2020;10(8):93-104. eISSN 2391-8306. DOI http://dx.doi.org/10.12775/JEHS.2020.10.08.011 https://apcz.umk.pl/czasopisma/index.php/JEHS/article/view/JEHS.2020.10.08.011 https://zenodo.org/record/3969370 The journal has had 5 points in Ministry of Science and Higher Education parametric evaluation. § 8. 2) and § 12. 1. 2) 22.02.2019. © The Authors 2020; This article is published with open access at Licensee Open Journal Systems of Nicolaus Copernicus University in Torun, Poland Open Access. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author (s) and source are credited. This is an open access article licensed under the terms of the Creative Commons Attribution Non commercial license Share alike. (http://creativecommons.org/licenses/by-nc-sa/4.0/) which permits unrestricted, non commercial use, distribution and reproduction in any medium, provided the work is properly cited. The authors declare that there is no conflict of interests regarding the publication of this paper. Received: 20.07.2020. Revised: 25.07.2020. Accepted: 01.08.2020. Relationship between the diet and psychiatric diseases such as depression, anxiety and attention-deficit hyperactivity disorder (ADHD) Magdalena Kozyra1, Patryk Zimnicki1, Justyna Kaczerska1, Natalia Śmiech1, Martyna Nowińska1, Joanna Milanowska2 (1) Student Research Group of Applied Psychology, Medical University of Lublin (2) Department of Applied Psychology, Medical University of Lublin *Address for correspodence: Staffa 24, 20-454 Lublin, telephone number: 695562174, e-mail address: madzia.kozyra.1221@poczta.onet.pl ORCID ID and E-mail Magdalena Kozyra https://orcid.org/0000-0002-0260-4102 madzia.kozyra.1221@poczta.onet.pl Patryk Zimnicki https://orcid.org/0000-0002-5808-8661 patryk.zimnicki.97@o2.pl Justyna Kaczerska https://orcid.org/0000-0003-2642-9377 justynakaczerska@gmail.com Natalia Śmiech https://orcid.org/0000-0002-8920-7969 natalia.smiech@gmail.com Martyna Nowińska https://orcid.org/0000-0002-8167-698X m.nowinska98@gmail.com Joanna Milanowska https://orcid.org/0000-0001-9741-1583 joannamilanowska@umlub.pl ABSTRACT Introduction: Some people try to treat psychiatric diseases such as attention-deficit hyperactivity disorder (ADHD), depression and anxiety by practising some diets. But do they even work and have any scientific confirmation? The aim of the study: The aim of this study is to find out the relationship and influence of the diet on psychiatric diseases such as ADHD, depression and anxiety. Material and method: The research of the scientific articles was made on a database of PubMed and Google Scholar. Description of the state of knowledge: The results indicate that the lack of some nutrients such as vitamins B1, B2, B3, B6, B12, C, A, D, E, folic acid, zinc, iodine, selenium, iron, calcium, potassium, phosphorus, magnesium and chrome may increase the risk of having depression symptoms. Unhealthy diet full of trans fats, red meat and lacking of fruit and vegetables may also lead to depression. Similar results were find due to the anxiety level and the diet. When it comes to ADHD, children with this disease had lower level of vitamins B12, B6, D and folic acids. Among the newly diagnosed celiac disease people, the majority showed ADHD symptoms. After the introduction of the gluten-free diet, the symptoms of the disease subsided. Summary: The results show the huge influence of the diet on the diseases such as depression, anxiety and ADHD. Key words: attention-deficit hyperactivity disorder, depression, anxiety, diet