monounsaturates

Monounsaturates, or monounsaturated fats, are fats in which most fatty acids contain a single carbon–carbon double bond. They are one of the major categories of dietary fats, along with saturated and polyunsaturated fats. The most common monounsaturated fatty acid in the human diet is oleic acid (C18:1).

Chemical structure and properties: Monounsaturated fatty acids have one double bond in their hydrocarbon chain, which reduces saturation compared with saturated fats. This structural feature makes the fats typically liquid at room temperature but able to solidify when chilled. They are generally more resistant to oxidation than polyunsaturated fats, aiding stability, though they can degrade with prolonged heat, light, or storage. Typical dietary sources contain a mix of fatty acids, but oleic acid dominates in many oils and foods.

Dietary sources and intake: Common sources include olive oil, canola (rapeseed) oil, peanut oil, avocados, and a variety of nuts and seeds. Many cooking oils labeled as high in monounsaturated fats emphasize oleic acid content. Monounsaturated fats are present in smaller amounts in other fats and foods as part of their overall fatty acid profile.

Health effects and diet: Replacing saturated fats with monounsaturated fats can lower low-density lipoprotein (LDL) cholesterol and may improve the overall lipid profile. Evidence from observational studies associates higher monounsaturated fat intake with reduced cardiovascular risk, while randomized trials show modest or context-dependent benefits. Diets emphasizing monounsaturated fats, such as the Mediterranean pattern, are commonly recommended as part of a balanced approach to heart health.

See also: polyunsaturated fats, saturated fats, trans fats.