Abstract
- Background
The impact of vitamin D supplementation on depressive symptoms remains uncertain. This study aimed to investigate the dose-dependent effects of vitamin D supplementation on depressive and anxiety symptoms in adults.
- Methods
Systematic searches were conducted in PubMed, Scopus, and Web of Science up to December 2022 to identify randomized controlled trials evaluating the effects of vitamin $\text{D}_3$ supplementation on depression and anxiety symptoms in adults. Using a random-effects model, standardized mean differences ($\text{SMD}$) were calculated for each $1000\text{ IU/day}$ of vitamin $\text{D}_3$ supplementation. The GRADE tool was used to assess the certainty of evidence.
- Results
The analysis included 31 trials with 24,189 participants. Each $1000\text{ IU/day}$ vitamin $\text{D}_3$ supplementation slightly reduced depressive symptoms in individuals with and without depression ($\text{SMD} = -0.32$, $95\%\text{ CI} = -0.43\text{ to }-0.22$; GRADE = moderate). The effect was more pronounced in those with depressive symptoms ($\text{SMD} = -0.57$, $95\%\text{ CI} = -0.69\text{ to }-0.44$, $n = 15$). The greatest reduction occurred at $8000\text{ IU/day}$ ($\text{SMD} = -2.04$, $95\%\text{ CI} = -3.77\text{ to }-0.31$). Trials with follow-up $\le 8\text{ weeks}$ ($\text{SMD} = -0.45$, $95\%\text{ CI} = -0.70\text{ to }-0.20$, $n = 8$) and $8\text{ to }\le 24\text{ weeks}$ ($\text{SMD} = -0.47$, $95\%\text{ CI} = -0.70\text{ to }-0.24$, $n = 15$) showed stronger effects compared to those lasting $24\text{ to }\le 52\text{ weeks}$ ($\text{SMD} = -0.13$, $95\%\text{ CI} = -0.28\text{ to }0.02$, $n = 5$) or longer than $52\text{ weeks}$ ($\text{SMD} = 0.14$, $95\%\text{ CI} = -0.16\text{ to }0.44$, $n = 3$) ($p\text{ group difference} < 0.001$). Vitamin $\text{D}_3$ supplementation had no significant effects on anxiety symptoms.
- Conclusions
In summary, this study suggests that vitamin $\text{D}_3$ supplementation may effectively reduce depressive symptoms in the short term. Further high-quality trials are warranted for a conclusive assessment of its impact on anxiety.
https://pmc.ncbi.nlm.nih.gov/articles/PMC11650176/