Plant-based diets linked to lower dementia risk in meta-analysis, but causality not proven
Mar 2nd 2026
A 2026 systematic review and dose-response meta-analysis of seven prospective studies covering 221,380 adults found that higher adherence to plant-based diets, especially those rich in healthful plant foods, was associated with a lower risk of cognitive impairment and dementia, but high heterogeneity and the observational nature of the data mean randomized trials are needed to confirm causality.
- Meta-analysis pooled seven prospective cohort studies with 221,380 participants and 5,668 cases of cognitive impairment or dementia.
- Greater adherence to plant-based diets was associated with a 26% lower risk of cognitive impairment and dementia (pooled RR 0.74, 95% CI 0.56-0.97).
- Statistical heterogeneity across studies was high (I2 = 92.3%).
- Dose-response analysis found overall plant-based diet index and healthful plant-based diet index were inversely associated with risk, while an unhealthful plant-based diet index was associated with higher risk.
- Evidence comes from observational studies, so residual confounding and bias cannot be ruled out.
- Authors recommend large randomized controlled trials to test whether plant-based diets causally reduce dementia risk.