Omega-3 fatty acids have gained recent attention due to the increased interest in wellness and disease prevention. They are thought to play a role in reducing inflammation, having affects on the body’s immune response and potential impact on cell functions throughout the body. Some of the disease conditions that omega-3 fatty acids are thought to benefit include cancer, kidney and heart disease, skin diseases, allergic conditions and arthritis. Omega-3 fatty acids are also thought to play an important role in normal processes such as the development of the eyes and neurologic system.
Definition of omega-3 fatty acids
Omega-3 fatty acids (e.g. alpha-linolenic acid) are a type of polyunsaturated fat in which the first double bond is located on the third carbon molecule. This is in contrast to omega-6 fatty acids (e.g. linoleic acid), in which the first double bond is at the sixth carbon. This difference conveys a different structure and different characteristics to the fatty acid. In animals, there are two important omega-3 fatty acids, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). These are long chained fatty acids that cannot be metabolized by animals and must be supplied in the diet.
Dietary sources of omega-3 fatty acids
There are two ways these omega-3 fatty acids can be obtained in the diet. The first dietary source of DHA and EPA is directly from coldwater fish such as salmon, herring, and mackerel. The second dietary source of DHA and EPA is from alpha-linolenic acid (ALA) found in some vegetable oils. ALA can be metabolized to DHA and EPA, but the body is not very efficient at doing so. For that reason, recommendations are made to supplement the diet with preformed DHA and EPA from fish oils.
The role of omega-3 fatty acids in animals.
EPA and DHA are important omega-3 fatty acids for both the structure and function of cell membranes throughout the body. From a structural point of view, EPA and DHA help control the stability and fluid nature of the cell membrane. From a functional standpoint, they play a role in the activity of many membrane-associated enzymes. DHA is very important for development of the brain and retina and both sites contain the highest levels of DHA in the body.
The benefit of having a higher concentration of omega-3 fatty acids in the membrane is that breakdown products of omega-3 fatty acids are, in general, less potent inflammatory mediators that those derived from omega-6 fatty acids. For example, use of omega-3 fatty acid supplements in cats that are itching can show benefits with cats itching less within 1-2 weeks; however, it may take 6-12 weeks before a favorable response is seen. This response is thought to be due to decreased production of inflammatory mediators that cause itching to occur.
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