Abstract
BACKGROUND: This study investigates the association between dietary flavonoid intake and the incidence of mild cognitive impairment (MCI) through a matched case-control design. METHODS: Dietary intake was assessed using a food frequency questionnaire, comparing the intake of flavonoids between individuals with MCI and those with normal cognitive function. Logistic regression analysis was employed to evaluate the correlation between dietary flavonoid intake and the risk of MCI. Additionally, blood concentrations of S100β, a marker of the blood-brain barrier (BBB) integrity, were measured using electrochemiluminescence immunoassay, and Pearson correlation analysis was conducted to explore the relationship between dietary flavonoid intake and blood S100β levels. RESULTS: Compared to participants with normal cognition, those with MCI had significantly lower dietary intakes of total flavonoids, isoflavones, daidzein, glycitein, genistein, kaempferol, myricetin, flavonols, and anthocyanidins, while the intake of peonidin was significantly higher. Univariate logistic regression analysis indicated that high dietary intake of total flavonoids, isoflavones, daidzein, glycitein, genistein, kaempferol, myricetin, and flavonols was negatively correlated with MCI, whereas peonidin intake was positively correlated with MCI. Multivariate logistic regression analysis confirmed these findings. Pearson correlation analysis revealed a significant negative correlation between dietary intake of kaempferol and myricetin and blood S100β levels. CONCLUSION: Increasing the dietary intake of total flavonoids, isoflavones, daidzein, glycitein, genistein, and flavonols appears to be a protective factor against MCI, while higher intake of peonidin is associated with an increased risk of MCI. The protective or adverse effects of these flavonoids may not be related to the permeability of the BBB. Myricetin and kaempferol intake may protect cognitive function by maintaining BBB integrity.