Polyunsaturated
Encyclopedia : P : PO : POL : Polyunsaturated
A polyunsaturated fatty acid is one in which more than one double bond exists within the representative molecule. That is, the molecule has two or more points on its structure capable of supporting hydrogen atoms not currently part of the structure. Polysaturated fatty acids can assume a cis or trans conformation depending on the geometry of the double bond.
The lack of the extra hydrogen atoms on the molecule's surface typically reduces the strength of the compound's intermolecular forces, thus causing the melting point of the compound to be significantly lower. This property can be seen by comparing usually unsaturated vegetable oils, which remain liquid even at relatively low temperatures, to much more saturated butter, a substance which can solidify near room temperature. Trans fats are more similar to saturated fat than are cis fats in many respects, including the fact that they solidify at a higher temperature.
A fatty acid has a carboxylic acid at one end and a methyl group at the other end. Carbon atoms in a fatty acid are identified by Greek letters on the basis of their distance from the carboxylic acid. The carbon atom closest to the carboxylic acid is the alpha carbon, the next adjacent carbon is the beta carbon, etc. In a long-chain fatty acid the carbon atom in the methyl group is called the omega carbon because omega is the last letter of the Greek alphabet.
Omega-3 fatty acids have a double bond three carbons away from the methyl carbon, whereas omega-6 fatty acids have a double bond six carbons away from the methyl carbon. The illustration below shows the omega-6 fatty acid, linoleic acid.
Omega-3 fatty acids in fish oil, fish and seafood lowers the total amount of fat in your blood, which can lower your blood pressure and decrease the risk of getting cardiovascular diseases. Omega-6 fatty acids in sunflower oil and safflower oil also reduce the risk of cardiovasular disease, but can contribute to allergies and inflammation.
Polyunsaturated fat is the "healthiest" fat and the amount of it in your diet should be between 5% and 10% of your total food energy. You can find this fat in grain products, fish and sea food (herring, salmon, mackerel, halibut), soybeans, mayonnaise, soft margarine and fish oil. If you get too little of it, you can get ill[[Citing sources citation needed]].
Molecular description: Illustration of linoleic acid
See also
- Saturated fat
- Unsaturated fat
- *Monounsaturated fat
- * Polyunsaturated fat
- *Trans fat
External links
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