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Associations between plant-based dietary patterns and risks of cognitive impairment and dementia: a systematic review and dose-response meta-analysis
The association between dietary patterns and cognitive decline raises an important question: can plant-based diets mitigate the risk of cognitive impairment and dementia? While existing evidence is mixed, certain plant-based foods, such as refined carbohydrates and trans fats, have been implicated in increasing dementia risk.
This systematic review and meta-analysis aimed to quantitatively evaluate prospective cohort studies investigating the association between adherence to plant-based diets and the incidence of cognitive impairment and dementia. The research followed PRISMA guidelines and was registered under PROSPERO (No: CRD42024501334).
Studies up to December 2025 were examined, utilizing databases including AgeLine, CINAHL, Embase, MEDLINE, PsycINFO, Scopus, and Web of Science. The participant pool consisted of adults aged 20 years and older who had no baseline cognitive impairment.
Included studies assessed dietary patterns that were either characterized by increased consumption of plant-based foods with reduced animal-product intake or used established dietary indices: the overall plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI).
Three independent reviewers conducted data extraction and bias assessment, employing the GRADE approach to evaluate the certainty of the evidence. The statistical analysis used a random-effects model with restricted maximum likelihood to estimate pooled risk ratios and their associated confidence intervals. A dose-response meta-analysis was performed, utilizing two-stage dose-response regression techniques.
The findings from this meta-analysis, which included seven studies comprising 221,380 participants and 5,668 cases of incident cognitive impairment and dementia, revealed that individuals exhibiting higher adherence to plant-based diets had a reduced risk of cognitive decline (pooled risk ratio of 0.74; 95% confidence interval, 0.56-0.97; I2 = 92.3%) compared to those with lower adherence. Additionally, dose-response modeling indicated a negative correlation between PDI and hPDI and the risks of cognitive impairment and dementia, while uPDI showed a significant positive association.
In summary, this analysis suggests that greater adherence to healthful plant-based diets is linked to a lower risk of cognitive impairment and dementia. However, due to the remaining heterogeneity in the data and the limitations of observational study designs, further large-scale randomized controlled trials are necessary to establish a causal relationship. [NPID: Cognitive decline, dementia, plant-based]
Year: 2026
