In this review paper by Micha and Mozaffarian, the types of trans fatty acids (industrial and natural trans fatty acids) and the effects of trans fatty acid consumption on plasma lipoprotein-lipid levels, systemic inflammation, endothelial function, adiposity and plasma glucose-insulin homeostasis are discussed. Moreover, the relationships of trans fatty acid consumption with coronary heart disease and diabetes are also covered. Metabolic and signalling pathways that mediate the deleterious effects of trans fatty acid consumption are also described.