Oleic acid molecule rotating, animation. Oleic acid is one of the common fatty acids that make up oils and fats found in foods. It is particularly abundant in olive oil, from which it takes its name, and it is the most common fatty acid found in human adipose (fat) tissues. It is a monounsaturated omega-9 cis fatty acid, meaning that it has one carbon-carbon double bond nine bonds from the end of the molecule, and that the carbon chains are attached to the double bond on the same side. Double bonds cannot rotate, so this gives the molecule a permanent kink. This kink causes it to pack less densely than would be the case if it were straight, as in the trans form, which reduces the risk of atherosclerosis. A diet rich in cis fatty acids causes blood levels of high-density lipoprotein (HDL), or 'good cholesterol', to be higher than for a diet rich in trans fatty acids. See clip K003/7110 for the trans form of oleic acid, called elaidic acid.