C3 and metabolic dysfunction-associated steatotic liver disease: To further clarify the association of serum complement C3 levels with NAFLD, we divided all participants into quartiles according to their serum complement C3 levels: <1.07 g/L, 1.07–1.16 g/L, 1.17–1.26 g/L, and ≥1.27 g/L for quartile 1, 2, 3, and 4, respectively.