Fig. 2

Volcano plot of smoking index and metabolites & ESCC and metabolites (Adjusted for age and gender). a: association of smoking index and metabolites; b: association of ESCC and metabolites. Fold is the ratio of the mean metabolite content between the case group and the control group. The blue dots indicate FDR <  0.05 and fold < 1, and the red dots indicate FDR <  0.05 and fold > 1. The dashed line is the borderline of FDR = 0.05