The associations between fresh vegetable and fruit consumption and plasma and PET biomarkers in preclinical Alzheimer's disease: A cross-sectional and longitudinal study of Chinese population.

Background: The identification of the modifiable lifestyle factors including dietary habits in older adults of preclinical Alzheimer's disease (AD) and early effective interventions are of great importance.

Objectives: We studied whether the consumption of fresh vegetables and fruits was different between cognitively unimpaired (CU) and cognitively impaired (CI) population and mainly investigated the associations between vegetable and fruit consumption and PET and plasma AD biomarkers in older CU adults with higher β-amyloid (Aβ) burden.

Design, Setting, And Participants: Older adults with the age of 50-85 years were enrolled for a cross-sectional and longitudinal study. The groups depended on whether the participants were CU or CI. Partial participants whose habits remained unchanged were followed up.

Measurements: The consumption data of vegetables and fruits were collected using a validated self-reported questionnaire. We mainly investigated the associations between vegetable and fruit consumption and various biomarkers in CU participants with positive F-florbetapir PET scan (Aβ-PET), part of whom also underwent plasma AD biomarkers tests and F-MK6240 PET scan (tau-PET). Correlation and multiple linear regression analyses were used to investigate the associations between vegetable and fruit consumption and AD biomarkers.

Results: A total of 1433 participants were enrolled, of which CU accounted for 49.4 %. Most of the intake habits of vegetables and fruits was different between CU and CI participants. 177 CU participants with Aβ-PET positive were selected for the following study. Multiple linear regression analysis showed higher consumption of fresh vegetables (>200 g/d), dark vegetables (>100 g/d, ≥2d/week), fruits (>100 g/d), berries (>100 g/d) and grapes (>100 g/d) more or less had associations with the plasma biomarkers including Aβ40, t-Tau, p-Tau-181 and neurofilament light chain as well as amyloid and Tau PET biomarkers. Most of the habits were associated with the change of cognitive function after an approximately two-year follow-up. Especially, higher intakes of fruits and grapes correlated with both lower Aβ and Tau burden and inversely with cognitive decline after follow-up.

Conclusion: Our data indicates that higher consumption of vegetables, dark vegetables, fruits, berries and grapes is associated with amyloid and Tau PET and plasma biomarkers in preclinical AD participants and the changes of cognitive function after follow-up. Higher intakes of fruits (>100 g/d) and grapes (>100 g/d) may be more helpful for reducing the risk of AD development.