Higher Vitamin D Levels Lowers Dementia Risk, Finds Frontiers Study

A recent new meta-analysis published in the journal of Frontiers in Neurology suggests that higher serum vitamin D levels may be associated with a reduced risk of dementia. This research analyzed data from over 53,000 participants across 22 observational studies to clarify the relationship between vitamin D and cognitive decline.

The study systematically reviewed data from the Cochrane Library, PubMed, and Embase up to October 2024. This included studies spanning diverse populations and geographic regions, with participants monitored for the onset of dementia in relation to their blood vitamin D concentrations.

The individuals in the lowest vitamin D category underwent a 49% higher risk of developing dementia when compared to the individuals with the highest levels. This translated to a relative risk (RR) of 1.49 with a 95% confidence interval of 1.32 to 1.67. Heterogeneity among the studies was moderate (I² = 37.8%), which indicated some variation in the effect across different populations but reinforcing the overall trend.

This research conducted a dose–response analysis to explore whether incremental changes in vitamin D levels corresponded to measurable differences in dementia risk. The findings revealed a linear association, for every 10 nmol/L increase in serum vitamin D, the risk of dementia decreased by approximately 1.2% (RR = 0.988, 95% CI: 0.982–0.994).

While this effect is relatively small at the individual level, this research note that the public health implications could be more significant in populations with widespread vitamin D deficiency. No evidence of non-linear effects was observed, suggesting that risk reduction follows a steady, proportional pattern rather than a threshold effect.

This study examined subgroups to assess whether the association varied by age, sex, geographic location, or study design. Across these comparisons, the inverse relationship between vitamin D levels and dementia risk remained consistent, lending robustness to the findings. Other factors, like diet, sun exposure, and underlying health conditions, could also influence dementia risk.

Overall, the analysis reinforces the potential link between vitamin D and cognitive health, highlighting a small but consistent protective effect. These findings emphasize that while maintaining adequate vitamin D levels is important for overall health, randomized controlled trials are needed to confirm whether supplementation could directly reduce the risk of dementia.

Source:

Huang, Y., Chen, Y., Wu, Y., Wu, Y., Dai, X., Feng, J., & Li, X. (2025). Association of vitamin D with risk of dementia: a dose-response meta-analysis of observational studies. Frontiers in Neurology, 16(1649841). https://doi.org/10.3389/fneur.2025.1649841