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Omega-3 Fatty Acids - Nutrition (view source)
Revision as of 15:06, 22 April 2015
, 15:06, 22 April 2015no edit summary
==Toxicity==
==Toxicity==
Excess intake of ALA without a concurrent increase in LA resulting in a ratio below 2.6:1 (LA:ALA) may interfere with LA uptake into ceramide and the conversion of LA to AA,2 but toxicity studies are lacking.
Excess intake of ALA without a concurrent increase in LA resulting in a ratio below 2.6:1 (LA:ALA) may interfere with LA uptake into ceramide and the conversion of LA to AA,<ref name ="Zicker" /> but toxicity studies are lacking.
Dietary Sources
Excess EPA intake can cause platelet abnormalities and bleeding disorders in cats,<ref>Saker KE, ''et al''. (1998) '''Manipulation of dietary (n-6) and (n-3) ratio fatty acids alters platelet function in cats. '''''J Nutr ''1998;128:2845S-2647S</ref> though this effect has not been demonstrated in dogs.<ref>Boudreaux ML, ''et al.'' (1997)''' The effects of varying dietary n-6 to n-3 fatty acids ratios on platelet reactivity, coagulation screening assays, and antithrombin II activity in dogs.''''' JAAHA ''1997;33:235-243.</ref> Dogs fed excessive amount of the omega-3 long-chain polyunsaturated fatty acids, EPA and DHA, have shown impaired wound healing<ref>Mooney MA, ''et al.'' (1998)''' Evaluation of the effects of omega-3 fatty acid containing diets on the inflammatory stage of wound healing in dogs. '''''AJVR ''1998;59:859-863.</ref><ref>Scardino MS, ''et al.'' (1999)''' The effects of omega-3 fatty acid diet enrichment on wound healing. '''''Vet Derm ''1999;10:283-290. </ref>26,27 as well as impaired cellular immunity.<ref name="Wander">Wander RC, ''et al''. (1997)''' The ratio of dietary (n-6) to (n-3) fatty acids influences immune system function, eicosanoid metabolism, lipid peroxidation and vitamin E status in aged dogs.''''' J Nutr ''1997;127:1198-1205.</ref>
Specific seed and seed oils have varying concentrations of ALA; for example flaxseed oil provides 50% of the total fat as ALA while rapeseed (i.e., canola oil) provides 20% ALA.28 Terrestrial animal fats (associated with muscle, organ meat, eggs) are poor sources of ALA. Cold-water algae produce high concentrations of DHA, which is converted to EPA by marine fish after consumption; there is variation in EPA concentration between wild and farmed fish species.
==Dietary Sources==
Specific seed and seed oils have varying concentrations of ALA; for example flaxseed oil provides 50% of the total fat as ALA while rapeseed (i.e. canola oil) provides 20% ALA.<ref>USDA Nutrient Database. http://ndb.nal.usda.gov/ndb/</ref> Terrestrial animal fats (associated with muscle, organ meat, eggs) are poor sources of ALA. Cold-water algae produce high concentrations of DHA, which is converted to EPA by marine fish after consumption; there is variation in EPA concentration between wild and farmed fish species.
Recommendations for optimal ratios of omega-6 to omega-3 fatty acids are provided to pet food manufacturers, but an optimal amount of ALA has not been determined. Diets with higher levels of polyunsaturated fat (ALA, EPA and DHA) are prone to oxidative damage and require larger concentrations of dietary antioxidants to prevent rancidity (fat oxidation) during processing and storage.
Recommendations for optimal ratios of omega-6 to omega-3 fatty acids are provided to pet food manufacturers, but an optimal amount of ALA has not been determined. Diets with higher levels of polyunsaturated fat (ALA, EPA and DHA) are prone to oxidative damage and require larger concentrations of dietary antioxidants to prevent rancidity (fat oxidation) during processing and storage.
Diagnosing Omega-3 Fatty Acid Deficiency
Diagnosis of ALA and DHA deficiency is difficult to make clinically and evaluation of dietary intake is often used to demonstrate inadequate intake. Plasma lipid profiles may show low circulating concentrations of ALA and DPA though normal reference intervals have not been established.
==Diagnosing Omega-3 Fatty Acid Deficiency==
Diagnosis of ALA and DHA deficiency is difficult to make clinically and evaluation of diet is often used to demonstrate inadequate intake. Plasma lipid profiles may show low circulating concentrations of ALA and DPA though normal reference intervals have not been established.
==References==
==References==