A flavonoid-rich diet is associated with lower risk and improved imaging biomarkers of nonalcoholic fatty liver disease: a prospective cohort study

BACKGROUND: Mechanistic studies and short-term randomized trials suggest higher intakes of dietary flavonoids may protect against nonalcoholic fatty liver disease (NAFLD). OBJECTIVES: We aimed to perform the first population-based study with long-term follow-up on flavonoid consumption, incident NAFLD, and validated NAFLD biomarkers. METHODS: In a prospective study, we assessed the associations between flavonoid intake based on ≥2 24-h dietary assessments and NAFLD risk among 121,064 adults aged 40-69 y by multivariable Cox regression analyses. We further assessed the associations between flavonoid intake and magnetic resonance imaging-derived liver fat (a subset of n = 11,435) and liver-corrected T1 values (cT1; a subset of n = 9570), a marker of steatosis, more sensitive to inflammatory pathology. RESULTS: Over 10 y of follow-up, 1081 cases of NAFLD were identified. Participants in the highest quartile (Q4) of the flavodiet score reflecting the consumption of foods high in flavonoids, had a 19% lower risk of NAFLD compared to the lowest quartile (Q1) [hazard ratio (HR) (95% confidence interval (CI): 0.81 (0.67, 0.97), P-trend = 0.02)]. Moreover, participants in the Q4 of the flavodiet score had lower liver fat and cT1 values than those in Q1 (liver fat: relative difference Q1 compared with Q4: -5.28%, P-trend = <0.001; cT1: relative difference Q1 compared with Q4: -1.73%, P-trend = <0.001). When compared to low intakes, high intakes of apples and tea were associated with lower NAFLD risk [apples: HR (95% CI): 0.78 (0.67, 0.92), P-trend = <0.01; tea: HR (95% CI): 0.86 (0.72, 1.02), P-trend = 0.03)]. Additionally, when compared to low intakes, high apple, tea, and dark chocolate intakes were significantly associated with lower liver fat values, whereas high tea and red pepper intakes were significantly associated with lower cT1 values. CONCLUSIONS: The consumption of flavonoid-rich foods was associated with a reduced risk of NAFLD among middle-aged adults.