Optimizing Vitamin D Levels: A Real-World Analysis of Supplementation Efficacy and Patient Outcomes

# Background Vitamin D plays a crucial role in numerous metabolic processes and is essential for overall health. Clinical conditions, ideal threshold values and optimal dose of supplementation remain a topic of discussion. This study presents a real-world analysis of Vitamin D optimization in a diverse patient population. # Aim The primary objectives of our real-world study in primary care patients supplemented with vitamin D were to assess the effectiveness of different strategies in achieving optimal serum vitamin D levels and to identify factors that influence changes in vitamin D levels in patients with different clinical conditions. # Results Among the 22 patients receiving only a maintenance dose, 59% exhibited an inadequate response (either low or high), and in 36.3% of cases, this remained unexplained even after analyzing risk factors for vitamin D deficiency. Notably, one patient showed no increase in vitamin D levels three months after a controlled depot dose of 100,000 units. Despite supplementation, a significant subset of patients failed to reach optimal levels, suggesting potential resistance to conventional approaches or poor adherence. # Conclusion We suggest that adherence to supplementation was one of the critical factors in achieving target levels, but there must be other factors. Starting with supervised “depots” of vitamin D and improved patient education for maintenance dose helps to exclude the probably very high adherence problems. This real-world analysis highlights the complexities of vitamin D optimization and suggests the need for more complex research studies, when to supplement and how to do it. Our study shows the importance of monitoring Vitamin D levels 2–3 months after the first substitution for finding the optimal dose. PEER REVIEWED ARTICLE Peer reviewers: Dr Stefan Zechmann, Stoffwechselzentrum St. Gallen, friendly Docs AG, St. Gallen Prof. Dr Reto Krapf, Chief Medical Officer at Medisyn SA, Kriens Received on January 31, 2025; accepted after peer review on March 12, 2025; published on March 17, 2025.