Omega-3 is a type of fatty acid essential to the functions of many living organisms, including humans. It cannot be manufactured by the body and must be obtained through the diet from fish oil such as mackerel, salmon, tuna and cod. The average American diet is actually deficient in omega-3. A higher consumption can improve such physiological functions as the immune system and skin health.
Molecular Structure
All fatty acids are long chains of carbon atoms bonded together. One carbon atom can contain up to four bonds. It bonds to the two carbon atoms on either side and two separate hydrogen atoms sticking out from the other ends. But sometimes these carbon atoms will double bond with each other. This uses up a bond that would otherwise connect to a hydrogen atom.
A polyunsaturated fatty acid signifies that there are multiple double bonds in its structure. By contrast, monounsaturated fat contains only one double bond, and saturated fat contains none. Omega-3 is a specific kind of polyunsaturated fatty acid. Its name derives from the fact that the first double bond occurs on the third carbon-carbon bond where some of the hydrogen atoms are missing.
Features
Because of the single bonds, saturated fat can pack tightly together. But the more double bonds a fatty acid contains, the longer and more spread out its chemical structure will be. In addition, the double bonds are much tougher to break than single bonds; in omega-3 they are still allowed to maintain a wry flexibility. These properties allow omega-3 to be used for many of the body's important functions.
Types
The two main types of omega-3 fatty acids are eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA. They are only found in fatty fish and marine animals. Some plants and seeds contain another omega-3 fatty acid called alpha-linolenic acid, or ALA. Each type has a different molecular structure. ALA, for example, is shorter and has fewer double bonds. However, it is oxidized, or "burned," by the cells before it can affect metabolic activity, so it cannot be used for the same functions. ALA can be converted into DHA and EPA in the body, but it is an inefficient conversion process, occurring at a rate of less than 5 percent in adults.
Absorption
Once it is digested, according to Doctor of Sciences Joyce A. Nettleton, omega-3 is absorbed by the tissue and incorporated into the protective membrane of the cells, where it affects the metabolic activities within the cell. At times it restrains certain activities, but it often facilitates functions instead.
Function
Brain function is perhaps omega-3's most integral and important structural function. The cell membrane of neurons is 20 percent omega-3 fatty acids. As electrical signals jump across a physical gap from one neuron to the other, they must first pass through these membranes. DHA is believed to make the membranes more elastic, which allows a channel to change shape and open up within them. Only DHA is flexible enough to completely fulfill this function. Furthermore, omega-3 fatty acids can be incorporated into the retina of the eye to assist with visual function or the heart to regulate electrical activity and normalize heart rhythm. It is also used for inflammatory responses and to maintain the oil that lubricates the skin.
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