Vitamin D deficiency and depressive episodes in adolescents and young adults: systematic review and meta-analysis

BackgroundWe conducted a systematic review and meta-analysis to examine the relationship between vitamin-D deficiency and depression in adolescents and young adults. MethodsWe searched academic databases and reference lists from inception to July 2023, limited to English studies. We extracted data and assessed study quality using the Newcastle-Ottawa Quality-Assessment-Scale of Cohort Studies. We used random-effects meta-analyses to determine vitamin-D serum levels in depressed vs. non-depressed participants (mean difference) and odds ratio for vitamin-D categories (insufficiency and deficiency) and for gender and age subgroup analyses. We assessed statistical heterogeneity using I2. ResultsFrom 9,369 citations, we included seventeen studies (2010-2023). Mean sample size was 32,844 (range: 51 to 483,683). Meta-analysis of six studies showed that depressed individuals had lower vitamin-D levels than non-depressed individuals, mean difference = -7.99 nmol/L (95%CI: -14.44 to -1.55; p=0.02; I{superscript 2}=79%). Among the 11 studies not in the meta-analysis, ten found that vitamin-D insufficiency (50-75 nmol/L) and deficiency (<50 nmol/L) were significantly associated with depression. This association was stronger among female participants (OR=1.39, 95%CI: 1.33 to 1.45, I2=88%) and young adults (OR=1.25, 95%CI: 1.18 to 1.33, p<0.001, I2=94%). LimitationsOur included studies ranged in sample size, which may influence the interpretation and generalizability of the results. ConclusionsOver half of the studies indicated that vitamin-D insufficiency and deficiency are significantly associated with depression, with important variations by gender and age.