Epidemiological studies indicate that higher intakes of flavonoids are associated with reduced stroke risk, however, which subtypes play significant roles to protect against stroke remain unclear. A systematic literature search in PubMed and Web of Science databases was performed up to Oct. 2021. Flavonoids or their subtypes (flavanol, flavanone, flavone, flavan-3-ol, isoflavone, or anthocyanin) were paired with stoke as the search term. Multivariate-adjusted relative risks (RRs) with 95% confidence intervals (CIs) for the highest versus the lowest category were pooled by using a randomeffects model. Dose-response analysis was implemented by using a restricted cubic spline regression model. Ten independent prospective cohort studies with 387,076 participants and 9,564 events were included. Higher intakes of flavanones were inversely associated with stroke risk (RR = 0.85; 95%CI: 0.78, 0.93). Dose-response analysis showed that 50 mg/day increment of flavanones was associated with 11% reduction in stroke risk (RR = 0.89; 95%CI: 0.84, 0.94). Flavan-3-ols was marginally inversely associated with stroke risk (RR = 0.92; 95%CI: 0.82, 1.02). Dose-response analysis showed that 200 mg/day increment of flavan-3-ols was associated with 14% reduction in stroke risk (RR = 0.86; 95%CI: 0.75, 0.98). The non-significant association was observed with respect to other flavonoid subclasses. This study demonstrated higher intakes of flavanones and flavan-3-ols were associated with a lower risk of stroke. Dietary intakes of lemon and citrus rich in flavanones and flavan-3-ols might have beneficial functions for the protection against stroke. The findings of these associations of the present study need to be confirmed in other regions and ethnic origins.dose-response analysis, flavonoid subclass, meta-analysis, stroke risk
| INTRODUCTIONFlavonoids are widely found in fruits, vegetables and other plants. The main food sources of flavonoids include tea, citrus, berries, apples and wine (Kim, Vance, & Chun, 2016). Over the past few decades, plenty of people have recognized the importance of fruits and vegetables for health and are dedicated to knowing which compounds have a significant impact on the prevention of non-communicable diseases (Perez-Vizcaino & Fraga, 2018). Epidemiological studies have shown inverse associations between total flavonoids intake and chronic metabolic diseases, including coronary heart disease (CHD), cancer and stroke