Association of vegetable and fruit intake with risk of dementia: 3 prospective studies and meta-analysis of cohort studies.

BACKGROUND: Evidence linking intake of total and specific types of vegetable and fruit to dementia remains scarce.

OBJECTIVES: This study aimed to examine associations between intake of total and specific subgroups of vegetables and fruits and dementia risk across 3 prospective cohorts and a meta-analysis.

METHODS: Data were drawn from the Health and Retirement Study (HRS), the Framingham Heart Study Offspring Cohort (FOS), and the Whitehall II Study (WHII). Mean daily intakes of total vegetables and fruits, and 7 subgroups, were assessed using food frequency questionnaires. Incident dementia was identified using cohort-specific definitions. Cox regression models were used to estimat hazard ratios (HRs) and 95% confidence intervals (CIs). We also performed a meta-analysis that incorporated our results and findings from 13 previous cohort studies.

RESULTS: Among 18,339 participants aged ≥45 y (HRS: 6750; FOS: 3068; WHII: 8521), 936 dementia cases occurred over an average 7-13 y follow-up period. After multivariable adjustment, intake of total fruits and vegetables was associated with a lower risk of dementia in the highest compared with the lowest tertile (HR T3 compared with T1 was 0.74, 95% CI: 0.61, 0.89, P-trend = 0.165). Additionally, green leafy vegetables demonstrated a protective association (pooled HR per serving increment: 0.82; 95% CI: 0.70, 0.96, P-trend = 0.015). No significant pooled associations were observed for other vegetable or fruit subgroups. Findings pooled from a meta-analysis of 222,108 participants showed that a higher intake of fruits and vegetables was associated with a lower risk of dementia compared with a lower intake (pooled HR highest compared with lowest: 0.80; 95% CI: 0.71, 0.91). Significant inverse associations were also observed for vegetable intake (pooled HR highest compared with lowest: 0.87; 95% CI: 0.82, 0.92) and fruit intake (pooled HR highest compared with lowest: 0.90; 95% CI: 0.85, 0.95).

CONCLUSIONS: Our study supports an inverse association of intake of vegetables and fruits with dementia risk. Further studies on specific subgroups are warranted. This meta-analysis was registered at PROSPERO as CRD42024525765.