Vitamin D deficiency associated with depression in adolescents and young adults, stronger in females

BackgroundWe conducted a systematic review and meta-analysis to examine the association between vitamin D deficiency and depression in adolescents (10-17 years) and young adults (18-39 years). MethodsWe searched databases and reference lists (inception to October 2025, limited to English studies). We extracted data and assessed study quality using the Newcastle-Ottawa Scale. We used random-effects meta-analyses to determine mean difference scores in vitamin D serum levels (depressed vs. non-depressed), odds ratios for vitamin D categories (insufficiency and deficiency), and subgroup analyses (gender and age). We assessed statistical heterogeneity using I2, with fixed-effect modeling as a sensitivity analysis. ResultsFrom 11,309 citations, we found 20 studies between 2010 and 2025 (mean=27,956; range: 51 to 483,683). Twelve studies (60%) found that vitamin D insufficiency (50-75 nmol/L) and deficiency (<50 nmol/L) were significantly associated with depression. Our meta-analysis revealed that the depressed population of young adults and adolescents had lower mean vitamin D levels than non-depressed participants (random-effect MD=-17.77 nmol/L [-30.12,-5.42]; p<0.001; I{superscript 2}=95%). We found a significant association between depression and vitamin D deficiency (random-effect OR=2.06 [1.02, 4.17], p<0.001; I2=95%) but no association with vitamin D insufficiency (random-effect OR=0.94 [0.74, 1.21]; I2=0%). Fixed-effect and random-effects models produced consistent results. Female participants had a stronger association (random-effect OR=1.88 [1.29, 2.74], I2=97%) and no significant association among those aged 25 to 39 years old (random-effect OR=1.14 [0.78, 1.65], p<0.001, I2=94%). ConclusionOur systematic review suggested that vitamin D deficiency is significantly associated with depression, with important variations by sex and age.