We found that the medium (interquartile range) of serum complement C3 levels was 1.25 (1.16–1.36) g/L in NAFLD patients with normal range of serum ALT, but the levels increased to 1.33 (1.23–1.46) g/L in NAFLD patients with elevated serum ALT (Mann-Whitney U test, P < 0.001). Here, C3 is linked to metabolic dysfunction-associated steatotic liver disease.