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==What are Omega-3 Fatty Acids?==

==What are Omega-3 Fatty Acids?==

<font color="red">Omega-3 fatty acids are a family of polyunsaturated straight-chain hydrocarbons that have a double bond in the third carbon-carbon bond (n-3) when counted from the methyl end of the molecule. FIGURE to illustrate this, pointing out the methyl end and the omega bond</font> Only plants have the ability to add double bonds in the n-3 position. There is speculation that fatty acids belonging to the n-3 family, specifically alpha-linolenic acid and docosahexaenoic acid, exhibit essential fatty acid activity in dogs and cats.

<font color="red">Omega-3 [[Fatty Acids Overview - Nutrition|fatty acids]] are a family of polyunsaturated straight-chain hydrocarbons that have a double bond in the third carbon-carbon bond (n-3) when counted from the methyl end of the molecule. FIGURE to illustrate this, pointing out the methyl end and the omega bond</font> Only plants have the ability to add double bonds in the n-3 position. There is speculation that fatty acids belonging to the n-3 family, specifically alpha-linolenic acid and docosahexaenoic acid, exhibit essential fatty acid activity in dogs and cats.

'''Alpha-linolenic acid (ALA)''' is an 18 carbon chain with double bonds at the n-3, n-6 and n-9 positions (written as 18:3n-3) that accumulated in skin phospholipids;<ref name ="Rees">Rees CA, ''et al.'' (2001) '''Effects of dietary flax seed and sunflower seed supplementation on normal canine serum polyunsaturated fatty acids and skin and hair coat condition scores. '''''Vet Dermatol'';12:111-117.</ref> '''docosahexaenoic acid (DHA)''' is a 22 carbon chain with doubles bonds at the n-3, n-6, n-9, n-12, n-15, and n-18 positions (written as 18:6n-3) that accumulates in the [[Eye - Anatomy & Physiology#The Wall (retina, uvea and sclera)|retina]] during growth and development.<ref name="Zicker">Zicker SC, ''et al.'' (2012)''' Evaluation of cognitive learning, memory, psychomotor, immunologic, and retinal functions in healthy puppies fed foods fortified with docosahexaenoic acid–rich fish oil from 8 to 52 weeks of age. '''''JAVMA'' 2012;241:583-594.</ref> Alpha-linolenic acid undergoes an initial desaturation by hepatic Δ-6 desaturase followed by elongation and another desaturation to form '''eicosapentaenoic acid (EPA; 20:5n-3)'''.<ref name="Dunbar">Dunbar BL and Bauer JE. (2000) '''Conversion of essential fatty acids by delta-6 desaturase enzyme in dog liver microsomes. '''''J Nutr ''2000;132:1701S-1703S.</ref> Dogs have the ability to convert modest amount of ALA to EPA and supplementing with dietary ALA has been shown to increase plasma EPA levels in dogs;<ref name="Bauer">Bauer JE, ''et al.'' (1998)''' Dietary Flaxseed in Dogs Results in Differential Transport and Metabolism of (n-3) Polyunsaturated Fatty Acids.''''' J Nutr'' 1998;128:2641S-2644S.</ref> cats are unlikely to synthesise significant amounts of EPA from ALA given their limited hepatic Δ-6 desaturase enzyme activity.<ref name ="Sinclair">Sinclair AJ, ''et al.'' (1981)''' Essential fatty acid deficiency and evidence for arachidonate synthesis in the cat.''''' Br J Nutr'' 1981;46:93-93.</ref> Eicosapentaenoic acid is further elongated to form '''docosapentaenoic acid (DPA)''', which is released into circulation and taken up by the retina and brain where it is converted to '''docosahexaenoic acid (DHA)'''.<ref name="Alvarez">Alvarez RA, ''et al''. (1994) '''Docosapentaenoic acid is converted to docosahexaenoic acid in the retinas of normal and pred-affected miniature poodles. '''''Inv Ophthal Vis Sci ''1994;35:402-408.</ref>,<ref name="Pawlosky7">Pawlosky R, ''et al.'' (1994)''' Essential fatty acid metabolism in the feline: relationship between liver and brain production of long-chain polyunsaturated fatty acids.''''' J Lip Res'' 1994;35:2032-2040.</ref>

'''Alpha-linolenic acid (ALA)''' is an 18 carbon chain with double bonds at the n-3, n-6 and n-9 positions (written as 18:3n-3) that accumulated in skin phospholipids;<ref name ="Rees">Rees CA, ''et al.'' (2001) '''Effects of dietary flax seed and sunflower seed supplementation on normal canine serum polyunsaturated fatty acids and skin and hair coat condition scores. '''''Vet Dermatol'';12:111-117.</ref> '''docosahexaenoic acid (DHA)''' is a 22 carbon chain with doubles bonds at the n-3, n-6, n-9, n-12, n-15, and n-18 positions (written as 18:6n-3) that accumulates in the [[Eye - Anatomy & Physiology#The Wall (retina, uvea and sclera)|retina]] during growth and development.<ref name="Zicker">Zicker SC, ''et al.'' (2012)''' Evaluation of cognitive learning, memory, psychomotor, immunologic, and retinal functions in healthy puppies fed foods fortified with docosahexaenoic acid–rich fish oil from 8 to 52 weeks of age. '''''JAVMA'' 2012;241:583-594.</ref> Alpha-linolenic acid undergoes an initial desaturation by hepatic Δ-6 desaturase followed by elongation and another desaturation to form '''eicosapentaenoic acid (EPA; 20:5n-3)'''.<ref name="Dunbar">Dunbar BL and Bauer JE. (2000) '''Conversion of essential fatty acids by delta-6 desaturase enzyme in dog liver microsomes. '''''J Nutr ''2000;132:1701S-1703S.</ref> Dogs have the ability to convert modest amount of ALA to EPA and supplementing with dietary ALA has been shown to increase plasma EPA levels in dogs;<ref name="Bauer">Bauer JE, ''et al.'' (1998)''' Dietary Flaxseed in Dogs Results in Differential Transport and Metabolism of (n-3) Polyunsaturated Fatty Acids.''''' J Nutr'' 1998;128:2641S-2644S.</ref> cats are unlikely to synthesise significant amounts of EPA from ALA given their limited hepatic Δ-6 desaturase enzyme activity.<ref name ="Sinclair">Sinclair AJ, ''et al.'' (1981)''' Essential fatty acid deficiency and evidence for arachidonate synthesis in the cat.''''' Br J Nutr'' 1981;46:93-93.</ref> Eicosapentaenoic acid is further elongated to form '''docosapentaenoic acid (DPA)''', which is released into circulation and taken up by the retina and brain where it is converted to '''docosahexaenoic acid (DHA)'''.<ref name="Alvarez">Alvarez RA, ''et al''. (1994) '''Docosapentaenoic acid is converted to docosahexaenoic acid in the retinas of normal and pred-affected miniature poodles. '''''Inv Ophthal Vis Sci ''1994;35:402-408.</ref>,<ref name="Pawlosky7">Pawlosky R, ''et al.'' (1994)''' Essential fatty acid metabolism in the feline: relationship between liver and brain production of long-chain polyunsaturated fatty acids.''''' J Lip Res'' 1994;35:2032-2040.</ref>