Vitamin D Deficiency and Infantile Rickets Worldwide (2000–2025): Epidemiological Patterns, Public Health Gaps and Interventional Insights

Background: Vitamin D deficiency and rickets remain persistent public health challenges affecting infants globally, despite the preventable nature of the condition. Etiology is multifactorial—encompassing limited sun exposure, inadequate maternal and infant nutrition, cultural practices, and insufficient national supplementation programs. Disparities in incidence and outcomes continue to emerge across geographic, socioeconomic, and policy environments. Objectives: To examine global trends in the prevalence of vitamin D deficiency and rickets in infants from 2000 to 2025; to compare the clinical-radiological manifestation of rickets versus subclinical vitamin D deficiency; and to evaluate the effectiveness of public health interventions and supplementation programs. Methods: A structured literature review was conducted using PubMed, Scopus, and WHO databases. Inclusion criteria encompassed studies between 2000 and 2025 reporting on infantile vitamin D deficiency or rickets prevalence, clinical presentation, biochemical thresholds (<30 or <50 nmol/L), and the outcomes of vitamin D interventions. Studies on maternal supplementation and policy surveillance were also included. Statistical impact estimation was performed using comparative proportions of deficiency and rickets before and after interventions. Study quality and consistency were validated using a Foster plot. A PRISMA framework guided the selection process, identifying 30 studies for synthesis. Results: Globally, 15.7% of infants had serum 25(OH)D levels <30 nmol/L. The Eastern Mediterranean (up to 71.8%) and South Asia (40–80%) demonstrated the highest deficiency rates. Paradoxically, regions with abundant sunlight—such as Saudi Arabia, India, and Egypt—exhibited alarmingly high rates, reflecting behavioral and cultural barriers to UVB exposure. Clinical rickets incidence varied widely: Tibet (~30%), Egypt (~2–3%), and the UK (East Kent, 580 annual cases in 2023) showed a resurgence in overt rickets, while North America and Europe reported subclinical deficiency with rare clinical cases. Intervention studies showed that daily supplementation (e.g., 400 IU/day) reduced biochemical rickets incidence from ~5% to <1%. National policies and enforcement varied greatly: countries with surveillance and education (e.g., Germany, UK) showed better outcomes than regions with fragmented policies (India, UAE). Conclusions: Despite longstanding awareness, vitamin D deficiency and rickets remain global threats to infant health, particularly in sun-rich but culturally conservative or underserved regions. Targeted policies with universal supplementation, maternal education, and consistent monitoring are urgently needed to close the gap between knowledge and practice.