Unsaturated fat

An unsaturated fat is a fat otherwise known as fatty acid. As the name suggests, unsaturated fatty acids have at least one double bond within the fatty acid chain.

Types

A fatty acid chain is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond. Double bonds are formed, when hydrogen atoms are eliminated. In otherwords, a saturated fat has no double bonds, has the maximum number of hydrogens bonded to the carbons, and therefore is "saturated" with hydrogen atoms.

In cellular metabolism, unsaturated fat molecules contain somewhat less energy (i.e., fewer calories) than an equivalent amount of saturated fat. The greater the degree of unsaturation in a fatty acid (i.e., the more double bonds in the fatty acid) the more vulnerable it is to lipid peroxidation (rancidity). Antioxidants can protect unsaturated fat from lipid peroxidation.

Amounts of fat types in selected foods

Sources

Monounsaturated and polyunsaturated fats are found in higher proportions in plants and seafood and are usually liquid at room temperature as oils. The exceptions are certain tropical plant oils, such as coconut oil, palm oil, and palm kernel oil (which are high in saturated fat) and partially hydrogenated oils (a source of artificial trans fat).

Monounsaturated and polyunsaturated fats are found in a variety of foods, including:

Monounsaturated fats

• Avocados
• Mayonnaise and oil-based salad dressings
• Nuts (such as almonds, hazelnuts, peanuts, and pecans)
• Olives
• Seeds (such as pumpkin and sesame seeds)
• Soft margarine (liquid, spray, and tub)
• Vegetable oils (such as canola, olive, peanut, and safflower oils)

Polyunsaturated fats

• Fish (such as herring, mackerel, salmon, trout, and tuna)
• Mayonnaise and oil-based salad dressings
• Nuts (such as pine nuts and walnuts)
• Seeds (such as flax, pumpkin, sesame, and sunflower seeds)
• Soft margarine (liquid, spray, and tub)
• Vegetable oils (such as corn, cottonseed, soybean, and sunflower oils)

Dietary guidelines

• According to the Dietary Guidelines for Americans, there is evidence that diets in which unsaturated fats (especially polyunsaturated fats) are eaten in place of saturated fat and within the recommended daily limits for calories are associated with reduced blood levels of total cholesterol and low-density lipoprotein (LDL or "bad") cholesterol—which, in turn, are associated with a reduced risk of developing cardiovascular disease. Cardiovascular disease is the leading cause of death in both men and women in the U.S.
• The Dietary Guidelines for Americans recommend consuming less than 10% of calories per day from saturated fat. In addition, look for ways to replace saturated fat with monounsaturated and polyunsaturated fats when possible.

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See also

• Saturated fat
• List of unsaturated fatty acids
• Monounsaturated fat
• Polyunsaturated fat
• Trans fat
• Iodine number – a chemical analysis method to determine the proportion of unsaturated fat.