Effects of a Combined Vitamin D3 and Docosahexaenoic Acid Intervention on Cognitive Function and Blood Pyroptotic Biomarkers in Older Adults with Mild Cognitive Impairment: A 12-Month Randomized, Double-Blind, Placebo-Controlled Trial.
A 12-month combined vitamin D3 and DHA intervention significantly improved cognitive function and reduced blood pyroptotic biomarkers in older adults with mild cognitive impairment, with superior benefits compared to either supplement alone, potentially mediated by downregulating GSDMD.
Key Findings
Results
All intervention groups (VD3, DHA, and VD3+DHA) demonstrated significant improvements in cognitive function compared to placebo over 12 months.
360 participants with MCI were recruited and randomized into four groups: VD3 (800 IU/day), DHA (1 g/day), VD3+DHA combined, and placebo
355 participants completed the trial
Cognitive function was evaluated using the Wechsler Adult Intelligence Scale-Revised in China (WAIS-RC)
Improvements were significant compared to placebo (p < 0.05) at both 6-month and 12-month timepoints
Linear mixed-effects models (LMMs) were used to analyze longitudinal interaction effects
Results
The combined VD3 and DHA intervention yielded superior cognitive improvements compared to either single intervention alone.
The combined group showed superior scores for full-scale IQ (FIQ), performance IQ (PIQ), and verbal IQ (VIQ)
Several subtests also showed superior improvement in the combined group: information, comprehension, digit span, vocabulary, picture completion, block design, and picture arrangement
All comparisons between combined vs. single interventions were statistically significant (p < 0.05)
The VD3 dose was 800 IU/day and DHA dose was 1 g/day, both individually and in combination
Results
All intervention groups showed significant reductions in five blood pyroptotic biomarkers compared to the placebo group.
The five biomarkers measured were IL-1β, IL-18, NLRP3, Gasdermin D (GSDMD), and cleaved caspase-1
Biomarkers were measured by ELISA and Western blot at baseline, 6 months, and 12 months
All reductions were statistically significant compared to placebo (p < 0.05)
The combined VD3+DHA intervention significantly reduced all five pyroptotic biomarkers compared to each single intervention (all p < 0.05)
Results
Longitudinal reduction in GSDMD mediated the improvements in full-scale IQ (FIQ) observed with the interventions.
Structural equation modeling (SEM) was conducted to evaluate parallel mediation effects of blood biomarkers on cognitive improvements
GSDMD (Gasdermin D) is a key executioner protein in the pyroptosis pathway
This mediation analysis suggests a mechanistic link between pyroptosis suppression and cognitive benefit
Methods
The study design was a 12-month randomized, double-blind, placebo-controlled trial with four parallel arms.
Total of 360 participants with MCI were recruited and randomly assigned to four groups
Trial duration was 12 months with assessments at baseline, 6 months, and 12 months
The trial was double-blind and placebo-controlled
355 of 360 participants (98.6%) completed the trial
VD3 dose: 800 IU/day; DHA dose: 1 g/day
Background
The study aimed to assess whether pyroptosis pathway biomarkers are involved in the mechanisms by which VD3 and DHA affect cognition in MCI.
Pyroptosis is a form of inflammatory programmed cell death involving the NLRP3 inflammasome and Gasdermin D
Blood biomarkers included upstream (NLRP3), executioner (GSDMD, cleaved caspase-1), and downstream (IL-1β, IL-18) pyroptosis markers
The study used SEM to formally test mediation of cognitive outcomes through pyroptotic biomarkers
This represents a mechanistic investigation linking nutritional supplementation, neuroinflammation, and cognition
What This Means
This research suggests that taking vitamin D3 and the omega-3 fatty acid DHA together for 12 months can meaningfully improve thinking and memory abilities in older adults who have mild cognitive impairment (MCI), a condition that can sometimes progress to dementia. In this study of 355 older adults, those who took both supplements together showed greater improvements across multiple types of cognitive tests — including measures of verbal ability, memory, and visual-spatial skills — compared to those who took either supplement on its own or a placebo. All three active treatment groups (vitamin D3 alone, DHA alone, and the combination) outperformed the placebo group.
The study also found that all three supplement groups showed reductions in blood markers of a specific type of cellular inflammation called 'pyroptosis,' which involves proteins like NLRP3, Gasdermin D (GSDMD), and inflammatory molecules IL-1β and IL-18. Using statistical modeling, the researchers found that reductions in the protein GSDMD appeared to act as a pathway through which the combined supplement improved overall IQ scores, suggesting a possible biological mechanism linking the supplements to brain health benefits.
This research suggests that the combination of vitamin D3 (800 IU/day) and DHA (1 g/day) may work better together than either alone to support cognitive health in older adults with MCI, and that their benefits might partly operate by reducing inflammatory cell-death processes in the body. The relatively large sample size (360 participants), long duration (12 months), and rigorous double-blind placebo-controlled design strengthen confidence in these findings, though further research would be needed to understand long-term effects and whether these benefits extend to preventing progression to dementia.
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Yuan J, Yang R, Chen H, Zhao H, Chen X, Lou Z, et al.. (2026). Effects of a Combined Vitamin D3 and Docosahexaenoic Acid Intervention on Cognitive Function and Blood Pyroptotic Biomarkers in Older Adults with Mild Cognitive Impairment: A 12-Month Randomized, Double-Blind, Placebo-Controlled Trial.. Nutrients. https://doi.org/10.3390/nu18172777