A study investigating the association between vitamin D and depression among university students in 39 countries. Dania Abdul Razzak Kouider 1 , Nageeb Abdul Galil Hassan 1 , Yaser Mohammed Al-Worafi 1,2* 1 College of Pharmacy and Health Sciences, Ajman University, Ajman, UAE 2 College of Pharmacy, University of Science and Technology of Fujairah, Fujairah, UAE Abstract Objectives: The aim of this study was to explore the association between vitamin D deficiency and depression among university students and to identify the factors affecting this association. Methodology: A cross-sectional study was conducted between 1st January and end of March 2017 among university students from 39 different countries. Results: 699 students were participated in this study. The findings of this study found that 270 students (38.6%) had vitamin D deficiency with level less than 20. The findings of this study found that majority of students (99.9%) in this study had depression. The findings of this study found that there was no association between depression and vitamin D depression (p value=0.386). The findings of this study shows that there was a significant difference between the severe groups of depression and other classes in terms of prevalence of vitamin D deficiency (p value=0.000). Conclusion: The current study shows that there was no association between vitamin D deficiency and depression. On the other hand, there were significant associations between the severity of depression and vitamin D deficiency. Lack of sun exposure; diet and financial factors were the causes of vitamin D deficiency in this study. Further studies are highly recommended to investigate the causes of depression among students. Keywords: Vitamin D, Deficiency, Depression, Students. Accepted on June 5, 2019 Introduction Vitamin D deficiency affecting about half of the population worldwide [1-3]. Vitamin D deficiency affects all races as well as all age groups from infants till elderly [1-3]. Vitamin D deficiency is a serious health problem and associated with death in the general population [4]. Vitamin D deficiency reported as one of many risk factors that may cause depression [5,6]. Vitamin D supplementation may have a positive effect on the management of depression as they contribute to the neuroendocrine system regulation [7]. Across sectional study conducted by Jorde et al. [8] to investigate the association between vitamin D deficiency and depression as well as to evaluate the impact of vitamin D supplementation on the depression among 445 out patients at the University Hospital of North Norway found that there was a significant association between vitamin deficiency and depression. They found also that the vitamin D supplementation improved the depression symptoms [8]. Another study conducted by Guixiang et al. among 3916 adult’s patients in US found that there was no significant association between vitamin D deficiency and depression [5]. There are many factors contributing to the Vitamin D deficiency as reported in the literature: insufficient sun exposure on of the most important causes of Vitamin D deficiency; lack and insufficient amount of Vitamin D in the diet; Vitamin D malabsorption problems and others [6-8]. Depression is defined by American Psychiatric Association as: “a common and serious medical illness that negatively affects how you feel, the way you think and how you act ” [9]. Identification and management of Vitamin D deficiency among patients with depression are easy, not expensive, cost effective and may contribute to achieve the desired outcomes of treating patients with depression which lead to improve their quality of life [10]. There are few studies worldwide exploring the association between depression and Vitamin D deficiency. Therefore, the aim of this study was to explore the association between vitamin D deficiency and depression among university students. Methods Study design A cross-sectional study was conducted between 1st January and end of march 2017 among university students from the following countries: USA, Canada, Belgium, Russia, Sweden, ISSN 0970-938X www.biomedres.info Biomed Res 2019 Volume 30 Issue 4 655 Biomedical Research 2019; 30 (4): 655-659