Global folate deficiency among adolescent girls: A systematic review and meta-analysis

Abstract

INTRODUCTION: Adolescents have higher nutrient requirements than adults, as this stage accounts for approximately 40% of total adult weight gain, 45% of skeletal mass and about 15% of adult height. Adequate micronutrient intake is particularly essential for adolescent girls to support growth, reproductive health, and cognitive development. Adolescent folate deficiency disrupts hematopoiesis, causing megaloblastic anemia, and hinders growth, cognition, and immune function and becoming a major public health concern. OBJECTIVE: This global systematic review and meta-analysis aims to address the gap in comprehensive evidence on the prevalence of adolescent folate deficiency. METHODS: This systematic review was conducted and reported according to PRISMA guidelines. We conducted a systematic literature search in PubMed, HINARI, Science Direct, DOAJ, Google, and Google Scholar for studies reporting the prevalence of folate deficiency among adolescent girls up to August 2025. Study quality was assessed using the Newcastle-Ottawa Scale, and evidence certainty was evaluated using GRADE. Pooled prevalence estimates with 95% confidence intervals were calculated using a random-effects model (DerSimonian-Laird method). Heterogeneity was assessed with Cochrane Q and I² statistics. Publication bias was evaluated through visual inspection of funnel plots and Egger's regression test, and adjusted estimates were calculated using the trim-and-fill method. Meta-regression analyses were conducted to explore potential sources of heterogeneity. Sensitivity analyses were performed to assess the robustness of pooled estimates. RESULTS: The search strategy identified 1,498 records, of which 26 studies met the eligibility criteria and were included in this systematic review and meta-analysis. The pooled global prevalence of folate deficiency among adolescent girls was 26.9%(95% CI: 20.5-33.2), with substantial heterogeneity observed between studies (I² = 99.99%, p < 0.001). On average across included studies, approximately one-quarter of adolescent girls were classified as folate deficient, though the true prevalence varied markedly between settings.. The pooled prevalence of folate deficiency among adolescent girls varied across regions, with the highest rate observed in Africa at 35.5%. CONCLUSION: These findings revealed folate deficiency as a substantial global public health concern among adolescent girls with a disproportionately high burden in low-resource settings. Region-specific strategies are urgently needed to prevent folate deficiency among adolescent girls, particularly in low-resource settings. Implementing targeted nutritional interventions and public health policies is essential to reduce its associated health consequences in this vulnerable population.