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Early and Sustained Enrichment of Serum n-3 Long Chain Polyunsaturated Fatty Acids in Dogs Fed a Flaxseed Supplemented Diet


A study was conducted in dogs to assess n-3 long chain polyunsaturated fatty acid incorporation after feeding an α-linolenic (ALA)-rich flaxseed supplemented diet (FLX) for 84 days. Serum total phospholipids (PL), triacylglycerol (TG), and cholesteryl esters (CE) were isolated at selected times and fatty acid methyl esters were analyzed. Increased LA was seen in the FLX-PL fraction after 28 days and an expected decrease in PL–AA. Enrichment of ALA, eicosapentaenoic acid (EPA) and docosapentaenoic acid n-3 (DPAn-3) in the FLX-group occurred early on (day 4) in both PL and TG fractions but no docosahexaenoic acid (DHA) was found, consistent with data from other species including humans. In contrast, no accumulation of DPAn-3 was seen in serum-CE, suggesting that this fatty acid does not participate in reverse-cholesterol transport. The accumulation of DPAn-3 in fasting PL and TG fractions is likely due to post-absorptive secretion after tissue synthesis. Because conversion of DPAn-3 to DHA occurs in canine neurologic tissues, this DPAn-3 may provide a circulating reservoir for DHA synthesis in such tissues. The absence of DPAn-3 in serum-CE suggests that such transport may be unidirectional. Although conversion of DPAn-3 to DHA is slow in most species, one-way transport of DPAn-3 in the circulation may help conserve this fatty acid as a substrate for DHA synthesis in brain and retinal tissues especially when dietary intakes of DHA are low.

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Fig. 1



Arachidonic acid


Alpha-linolenic acid


Serum cholesteryl ester fraction


Docosahexaenoic acid


Docosapentaenoic acid, n-3


Ethylenediaminetetraacetic acid


Eicosapentaenoic acid


Flax seed supplemented diet


Linoleic acid


Serum phospholipid fraction


Sunflower seed supplemented diet


Serum triacylglycerol fraction


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This work was supported in part by Essential Nutrient Research Corp., Manitowoc, WI, USA and the Mark L. Morris Professorship in Clinical Nutrition at Texas A&M University.

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Correspondence to John E. Bauer.

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Dunbar, B.L., Bigley, K.E. & Bauer, J.E. Early and Sustained Enrichment of Serum n-3 Long Chain Polyunsaturated Fatty Acids in Dogs Fed a Flaxseed Supplemented Diet. Lipids 45, 1–10 (2010).

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  • Gas–liquid chromatography
  • Lipid analysis
  • Thin layer chromatography
  • Mammalian lipid biochemistry
  • Plasma lipids
  • Cholesteryl ester formation
  • Metabolism
  • n-3 Fatty acids
  • Nutrition