Diet quality attenuates the association between flavonoid intake and hepatic steatosis risk in the Framingham Heart...

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the leading cause of chronic liver disease worldwide. Flavonoids may offer protective benefits, but the role of overall diet quality in modulating this remains unclear. In this cross-sectional study, we analysed 2815 participants from the Framingham Heart Study. Hepatic steatosis was defined by liver:phantom ratio < 0·33 using multidetector computed tomography. Dietary intake was assessed using a validated FFQ, and intake of six flavonoid subclasses and total flavonoid was estimated using the USDA database. Logistic regression models evaluated associations between flavonoid intake quartiles and hepatic steatosis, adjusting for demographic and lifestyle covariates, followed by additional models adjusting for a priori dietary quality indexes: the Alternative Healthy Eating Index, the Mediterranean-style diet score and the Dietary Approaches to Stop Hypertension score. Higher intake of flavonols, flavan-3-ols, anthocyanidins, flavonoid polymers and total flavonoids is associated with lower odds of hepatic steatosis (P_trend < 0·05), with up to 40 % reduced odds at the highest quartiles before adjustment for diet quality. After adjustments, associations attenuated and lost statistical significance. The attenuation does not rule out a potential protective role of flavonoids; it may indicate that higher flavonoid intake is an important element of a broader healthy diet. Alternatively, the associations could be confounded by other components of diet which may independently reduce steatosis risk. Nonetheless, these findings underscore the importance of promoting flavonoid-rich diets in the context of overall healthy diet and support further investigation in prospective and interventional studies targeting MASLD prevention.