Polyunsaturated fat and monounsaturated fat are both unsaturated types of fat that may have health benefits when consumed in moderation. Getting more of these fats into the diet is easy, because they are present in high amounts in cooking oils and healthy snacks such as nuts and seeds. Both monounsaturated and polyunsaturated fats contain 9 calories per gram, just as all fats do.
Chemistry
The chemical difference between polyunsaturated fat and monounsaturated fat lies in the number of double bonds each contains. All fats contain a chain of carbon atoms with a methyl group on one end, and a carboxyl group on the other. In monounsaturated fats, there is one double bond located between two of the carbon atoms somewhere along the chain. In polyunsaturated fats, there are multiple double bonds found between carbon atoms in the chain. The more double bonds that exist, the more flexible the overall molecule is.
Types
Both monounsaturated fats and polyunsaturated fats can come in two configurations or shapes, called cis and trans. In monounsaturated fats, the cis version is called oleic acid and the trans version is known as eliadic acid. Polyunsaturated fats can have many cis and trans versions, depending on how many double bonds they contain and where on the chain of carbons those bonds are located. Common polyunsaturated cis molecules include the omega-6 fatty acids linoleic acid and arachidonic acid and the omega-3 fatty acids alpha-linolenic acid, or ALA, eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA. When polyunsaturated fats are heated and partially hydrogenated, dangerous trans fats can form.
Sources
Fats rarely have only one source, but some sources contain higher levels of particular fat types. For example, olive oil contains about 74 percent monounsaturated fat, 12 percent polyunsaturated fat and 14 percent saturated fat. Other foods high in monounsaturated fats include peanut oil, avocados, nuts and seeds. Foods high in polyunsaturated fats include safflower, sunflower, corn and soybean oil, walnuts, fatty fish and flaxseed. Omega-3 fatty acids are available in fish oil supplements for those who cannot get enough of them through diet alone.
Health Benefits
Monounsaturated and polyunsaturated fats can boost heart health when used in place of saturated and trans fats in the diet. Both types of unsaturated fat can lower overall cholesterol levels and LDL, or bad cholesterol, levels. Monounsaturated fats also may raise HDL, or good cholesterol, levels. The omega-3 type of polyunsaturated fats may decrease the risk of coronary heart disease, lower blood pressure and protect the heart from arrhythmia, according to MayoClinic.com.
Considerations
While both monounsaturated and polyunsaturated fats have health benefits, getting too much of any type of fat can be damaging to your health. Instead of increasing the intake of these fats, you should use them to replace saturated fats and trans fats in the diet. Total fat intake should remain under 35 percent of total calories, with the majority of these coming from monounsaturated and polyunsaturated fats.
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