omega_3_6 - Dietary Supplements Omega 3 and 6 Fatty Acids...

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Dietary Supplements Omega 3 and 6 Fatty Acids Background The essential fatty acids ( P oly U nsaturated F atty A cids, PUFA , omega 3 and omega 6) are required for the production of eicosanoids. Essential fatty acids are not made in the human body, but can be converted to others in the same family (omega 3 and omega 6 are these families). Eicosanoids are oxidized fatty acids with at least 20 carbons. The pathways for their production divide into prostaglandins (PG), thromboxanes (TXA) and leukotrienes (LT). PGs and TXA are generated by a pathway called the cyclooxygenase pathway (inhibited by aspirin), while the LTs are made by lipoxygenase. There are involved in modulating cardiovascular, pulmonary, immune, reproductive and secretory systems. The physiological action of the eicosanoids depends on the family produced. Fatty acids of 20 carbons with only 3 double bonds (C20:3, omega 6), result in PG1s and LT3, while those of 4 double bonds (C20:4, omega 6) go to PG2s, TX2 and LT4, and those of 5 double bonds (C20:5 omega 3) to PG3s, TX3 and LT5. The basic starting material for the omega 6 family is linoleic acid (18:2 omega 6). This can be converted to gamma linolenic acid (C18:3, omega 6, GLA ). GLA can be elongated to the C20:3 omega 6, Dihomo-gamma-linolenic acid (DHGLA). Linoleic acid and GLA are considered to be essential fatty acids. They are not made directly into eicosanoids, but do have physiological action because it can be converted to dihomo-gamma-linolenic acid. This reaction depends on the amount of other PUFAs. Arachidonic acid , ( AA ) the most common precursor to eicosanoids, (C20:4 omega 6), is made from dihomo-gamma-linolenic. It is found in the highest concentration in animal and milk products and is present in very low amounts in most plants. The omega 3 fatty acids have one 20 carbon fatty acid (eicosapentaenoic acid, EPA , C20:5) and one common 22 carbon with six double bonds (C22:6, Docosahexanoic acid, DHA ). The omega 3 fatty acids can be derived from alpha linolenic acid ( ALA , 18:3, omega 3). All of the fatty acids affect the metabolism of the others, so an imbalance of either 18:3 can reduce the amount of the other family (i.e., high intakes of fish oil with omega 3 will reduce the amount of omega 6 eicosanoids).
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This note was uploaded on 06/09/2010 for the course MFC 141 taught by Professor Horvath during the Summer '10 term at SUNY Buffalo.

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omega_3_6 - Dietary Supplements Omega 3 and 6 Fatty Acids...

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