Global and regional prevalence of vitamin D deficiency in population-based studies from 2000 to 2022: A pooled analysis of 7.9 million participants

**Background:** Vitamin D deficiency causes osteomalacia and is associated with numerous non-skeletal disorders including COVID-19, cardiovascular disease, diabetes, cancers, and autoimmune diseases. Despite growing recognition of its importance, no comprehensive global prevalence estimate existed. This study aimed to estimate global and regional prevalence of vitamin D deficiency in people aged ≥1 year from 2000 to 2022.

**Methods:** The authors systematically searched Web of Science, PubMed, Embase, Scopus, and Google databases on December 31, 2021, with an update on August 20, 2022, without language or time restrictions. They also included unpublished NHANES data (2015–2016 and 2017–2018) and manually searched references. Inclusion criteria: population-based studies reporting vitamin D deficiency prevalence in people aged ≥1 year, data collected after 2000, sample size >50. Excluded: specific occupational/educational populations, hospital-based populations, case-control studies, infants, pregnant women, and new mothers. A random-effects meta-analysis with Freeman-Tukey double arcsine transformation was used. Heterogeneity was assessed via I², subgroup analyses, meta-regression, and sensitivity analyses. Publication bias was evaluated with funnel plots and Egger's test. The study was registered with PROSPERO (CRD42021292586).

**Key Results:** Of 67,340 records screened, 308 studies with 7,947,359 participants from 81 countries were included. For serum 25(OH)D <30 nmol/L (202 studies, 7,634,261 participants): global prevalence 15.7% (95% CI 13.7–17.8). For <50 nmol/L (284 studies, 1,475,339 participants): 47.9% (95% CI 44.9–50.9). For <75 nmol/L (165 studies, 561,978 participants): 76.6% (95% CI 74.0–79.1). Prevalence decreased slightly from 2000–2010 to 2011–2022: <30 nmol/L from 17.6% to 14.1%; <50 nmol/L from 48.7% to 46.9%; <75 nmol/L from 77.1% to 75.9%. By WHO region, the Eastern Mediterranean had the highest prevalence (<30 nmol/L: 35.2%, 95% CI 29.6–41.0; <50 nmol/L: 71.8%, 95% CI 65.4–77.8) and the Region of the Americas the lowest (<30 nmol/L: 5.5%, 95% CI 3.5–7.8). By latitude, prevalence at 20–40°N was highest (<30 nmol/L: 23.1%; <50 nmol/L: 60.2%; <75 nmol/L: 84.9%). Lower-middle-income countries had the highest prevalence (<30 nmol/L: 26.7%, 95% CI 19.2–34.5). Females had higher prevalence than males (<30 nmol/L: 17.8% vs 13.6%; ratio 1.3, 95% CI 1.2–1.4). Winter-spring prevalence was 1.7 times (95% CrI 1.4–2.0) that of summer-autumn. Age group 19–44 had the highest prevalence of <30 nmol/L (18.2%). Meta-regression identified latitude, female proportion, sampling frame, detection assays, and season as contributors to heterogeneity. Sensitivity analyses confirmed stability. No significant publication bias was detected.

**Clinical Implications:** This study provides the first comprehensive global estimate of vitamin D deficiency prevalence across all ages and regions. With nearly half the global population having serum 25(OH)D <50 nmol/L and over three-quarters <75 nmol/L, the associated disease burden—including osteomalacia, rickets, infections, cardiovascular disease, and fractures—is substantial. The persistently high prevalence despite a slight decline over two decades indicates that current public health measures are insufficient. Priority actions include: public awareness campaigns, mandatory food fortification (the most cost-effective strategy), promoting safe sun exposure, and targeted supplementation for high-risk groups (women, residents of high-latitude regions, Eastern Mediterranean populations, and lower-middle-income countries). The scarcity of data from low-income countries and Africa (only 14 studies with 7,088 participants) highlights a critical evidence gap requiring urgent research investment.