Physical activity and vitamin D in children: a review of impacts on bone health and fitness

Abstract Objectives This review explores the relationship between physical activity and serum 25-hydroxyvitamin D (25(OH)D) levels in children and adolescents, highlighting the importance of vitamin D for bone health and muscle function. Content A narrative mini review was conducted by searching PubMed, Google Scholar, and Scopus for studies published from January 2000 to April 2024, focusing on children aged 5–18 years. Ten studies were reviewed, including five cross-sectional, three population-based, one longitudinal, and one randomized controlled trial. Overall, physically active children and teens were more likely to maintain sufficient 25(OH)D levels and demonstrated better physical fitness, especially in muscle strength, compared to their less active peers. One study linked higher vitamin D levels to increased bone mineral content in active adolescents, while another reported a positive connection between vitamin D and bone density. Risk factors for deficiency included limited sun exposure, low physical activity, sedentary behavior, and obesity, with the latter group being more prone to low vitamin D levels, which were negatively associated with fat mass. Interventions that increased physical activity were found to improve vitamin D levels. Summary and Outlook Regular physical activity, especially outdoor exercise, is associated with healthier vitamin D levels in children, supporting better bone health and physical fitness.