Heat maps of smoking-related metabolites in (A) men and (B) women. The heat map shows mean residues of smoking-related metabolites in CS, FS and NS and the reversibility after smoking cessation. The color of each cell in the heat map represents the relative mean concentration of each metabolite in NS, FS or CS. The number of samples in each group is provided. The bar besides the metabolite names indicates the reversibility of these metabolites after smoking cessation. aa: diacyl-; ae: acyl-alkyl-; C0: carnitine; CS: current smokers; FS: former smokers; lysoPC: acyl-phosphatidylcholine; NS: never smokers; PC: phosphatidylcholine; SM (OH): hydroxysphingomyeline.