On Jul. 11, 2003, the U.S. Food and Drug Administration (FDA) published a final rule in the Federal Register that amended its regulations on food labeling to require that trans fatty acids be declared in the nutrition label of conventional foods and dietary supplements.

FDA’s guidance documents, including this guidance, do not establish legally enforceable responsibilities. Instead, guidances describe the Agency’s current thinking on a topic and should be viewed only as recommendations, unless specific regulatory or statutory requirements are cited. The use of the word should in Agency guidances means that something is suggested or recommended, but not required.

Trans fatty acids, also known as trans fats, are made during partial hydrogenation of vegetable oils. Hydrogenation is the process by which hydrogen atoms are added to unsaturated sites on fatty acids, thereby, eliminating double bonds. Partial hydrogenation relocates some double bonds and hydrogen atoms end up on different sides of the chain. This type of configuration is called “trans” (means “across” in Latin).