Fatty acids are organic molecules composed of a long chain of carbon atoms with a carboxylic acid group at one end. Oleic acid is an unsaturated fatty acid with 18 carbon atoms and one double bond, commonly found in animal and vegetable fats. Trans fatty acids are produced by the partial hydrogenation of vegetable oils and are considered to be unhealthy due to their association with increased risk of cardiovascular disease. Lipids are a broad group of molecules that include fatty acids, and are important components of cell membranes and energy storage molecules.