Saturated Fats – Found predominantly in animal fats and tropical oils like coconut oil and in lesser amounts in all vegetable oils (and also made within your body, usually from excess carbohydrates). Saturated fats are structured so that all available carbon bonds are occupied by a hydrogen atom, which makes them highly stable and also straight in shape, so that they are solid or semisolid fat at room temperature. As a result of their unique composition, they are less likely to go rancid when heated during cooking and form dangerous free radicals that can cause a litany of ill health including heart disease and cancer.
Monounsaturated Fats – The monounsaturated fatty acid most commonly found in our food is oleic acid, the main component in olive oil and sesame oil, as well as the oil in almonds, pecan, cashews, peanuts, and avocados. Your body can also make monounsaturated fatty acids from saturated fatty acids when it needs them for various bodily functions.
Chemically, monounsaturated fatty acids are structured with one double bond (composed of two carbon atoms double bonded to each other). Because this bond causes the molecule to bend slightly, these fats do not pack together as easily as saturated fats, so they tend to be liquid at room temperature but become solid when refrigerated.
Like saturated fats, however, monounsaturated oils are relatively stable. They do not go rancid easily and hence can also be used in cooking.
Polyunsaturated Fats – polyunsaturated fatty acids have two or more double bonds. The two polyunsaturated fatty acids found most frequently in our foods are linoleic acid with two double bonds (called omega-6) and linolenic acid, with three double bonds (called omega-3). The omega number indicates the position of the first double bond)
Because your body cannot make these fatty acids, they are called ‘essential’ and must be obtained from foods. Polyunsaturated fatty acids have bends or turns at the position of the double bonds and hence do not pack together easily. They remain liquid, even when refrigerated.
Unpaired electrons located at the double bonds make these oils highly reactive. When they are subjected to heat or oxygen, as in extraction, processing and cooking, free radicals are formed. It is these free radicals, not saturated fats, that can initiate cancer and heart disease. As such, industrially processed polyunsaturated oil such as corn, safflower, soy and sunflower oils should be strictly avoided.
Manufactured foods, such as baked goods, some frozen foods, margarine, chips, fast food fries, and countless other products contain rearranged fatty acids called trans fats, which are produced artificially by bombarding polyunsaturated oils with hydrogen, a process called partial hydrogenation. This process makes the normally twisty polyunsaturated fatty acids straighten out and behave like saturated fats in foods. As a result, transfats have a longer shelf life. They pack together easily, so they are unnaturally solid at room temperature and can be used as spreads and shortenings. Because they can be made so cheaply and because their inclusion helps packaged foods to last nearly forever, the food industry prefers to use transfats made from cheap soy, canola, corn and cottonseed rather than more expensive animal fats or tropical oil.
So once again – the old construct of ‘follow the money’ applies here – transfats are much cheaper than the saturated fats to produce – ergo larger profits for the food processing companies.