Vitamin D Supplementation Enhances Cognitive Outcomes in Physically Active Vitamin D-Deficient University Students in the United Arab Emirates: A 10-Week Intervention Study

<b>Background/Objectives:</b> Vitamin D deficiency is a global epidemic. In certain populations, such as the United Arab Emirates (UAE), low nutritional intake of vitamin D, inadequate exposure to sunlight, and cultural dress codes can lead to deficiencies in blood vitamin D levels, predisposing them to musculoskeletal disorders, diabetes, and cardiovascular diseases. There are also notable associations between vitamin D deficiency, physical inactivity, and lower cognitive performance. The aim of this study was to determine how vitamin D status may affect physical inactivity and cognitive performance in a young UAE population. <b>Methods:</b> Primary data were obtained on vitamin D status, cardiorespiratory fitness, body composition, and blood profiles of students in the UAE. Following initial assessment, a cohort of vitamin D-deficient/insufficient individuals participated in a 10-week physical activity intervention (Group A), whilst another cohort was supplemented with 5000 IU vitamin D3 daily and an exercise intervention (Group B). Both groups underwent physiological and biochemical profiling, and the effects of vitamin D supplementation on cognitive function were assessed. Statistical analysis included paired samples <i>t</i>-tests between pre- and post-intervention values and the Wilcoxon signed rank test for within-group comparisons and the Mann-Whitney U test for between-group comparisons. <b>Results:</b> The findings suggest that physical exercise alone improves overall cardiorespiratory fitness, as shown by an increased VO₂ max (<i>p</i> < 0.05), while vitamin D supplementation combined with physical exercise did not significantly improve fitness over a 10-week period (<i>p</i> > 0.05). However, vitamin D combined with physical exercise significantly improved cognitive performance in Group B only, specifically in working memory, verbal memory, and cognitive flexibility (<i>p</i> < 0.05). <b>Conclusions:</b> This study highlights the need for targeted interventions such as physical exercise and vitamin D supplementation to be conducted at an early stage in order to improve physical and cognitive function and reduce the risk of disease.