trans9octadecenoic

Trans-9-octadecenoic acid, commonly called elaidic acid, denotes an 18-carbon monounsaturated fatty acid with a single trans double bond between carbon 9 and carbon 10. It is the trans isomer of oleic acid (cis-9-octadecenoic acid) and is often represented as 18:1 trans. The trans configuration gives a nearly linear molecule, in contrast to the bent shape of the cis form.

Natural occurrence and production: Trans-9-octadecenoic acid occurs in trace amounts in some fats from ruminant sources, but the predominant dietary source is industrially produced trans fats formed during partial hydrogenation of vegetable oils. It is commonly found in processed foods such as margarines, baked goods, snack foods, and fried items, though many products have reduced its levels due to health regulations.

Health and regulation: Intake of trans fats, including elaidic acid, has been linked to adverse cardiovascular effects, including increased LDL cholesterol and a higher risk of coronary heart disease. In response, many countries regulate artificial trans fats, require labeling, or have phased them out of widely sold food products to lower population-level exposure.

Chemical and dietary notes: As a reference trans isomer of octadecenoic acid, elaidic acid is used in lipid chemistry and nutritional studies to distinguish the effects of trans versus cis double bonds on metabolism and health.