Fatty acids are a simple lipid made up of a hydrophilic carboxylate group attached to a long hydrocarbon chain. These fatty acids are categorized as either saturated or unsaturated, depending on if all the carbons in the chain are fully bonded to hydrogen atoms (it is saturated with hydrogen) or if some carbons share bonds with each other (it is unsaturated). Monounsaturated fatty acids, often abbreviated MUFAs, are fatty acids where two carbons in this chain share one cis double bond, hence the term “mono.” The double bond causes a kink in the normally straight hydrocarbon chain, which prevents the fatty acids from packing tightly together. This bend lowers the melting point of the fatty acid and causes it to be liquid at room temperature.
Monounsaturated fatty acids can be synthesized in the body using saturated fatty acids. This is normally done by a chemical reaction that inserts a double bond between the ninth and tenth carbons in the chain. This reaction creates either oleic acid or palmitoleic acid, depending on which saturated fatty acid was used. Oleic acid is made from stearic acid and is the most abundant fatty acid in nature. Palmitoleic acid is made from palmitic acid. Both of these fatty acids can also be found in a variety of foods. Oleic acid is present in almost all animal and vegetable fats and oils. It is the most abundant fatty acid in many plant products such as olives, nuts, and a variety of vegetable oils such as olive oil, canola oil, and sunflower oil. Palmitoleic acid can be found in milk and coconut and palm oils.
Monounsaturated fatty acids have many roles in organisms. First they are an important source of energy for the body. Second, they are found in the cell membranes of most organisms, from bacteria and fungi to plants and animals. Because of their double bond they help the membrane stay fluid, making it easier to regulate the cell’s response to hormones, uptake of nutrients, and discharge of waste. Finally, they are also important for healthy skin. Oleic acid is the major type of fatty acid in oil secreted by skin glands to keep the skin moisturized.
The consumption of monounsaturated fatty acids has been shown to reduce cholesterol levels, however it is not as effective as polyunsaturated fatty acids such as linoleic acid. However, polyunsaturated fatty acids reduce both the LDL (unhealthy) and HDL (healthy) forms of cholesterol while monounsaturated fatty acids reduce LDL levels while not affecting or even raising HDL levels. High levels of monounsaturated fatty acids in the diet may reduce the risks of heart disease. Most doctors and researchers recommend replacing saturated fatty acids in the diet with healthier monounsaturated and polyunsaturated fatty acids.