Effects of Dietary Flaxseed Oil Supplementation on Equine Plasma Fatty Acid Concentrations and Whole Blood Platelet Aggregation
Hansen, R., Savage, C.J., Reidlinger, K., Traub-Dargatz, J.L., Ogilvie, G.K., Mitchell, D., and Fettman, M.J. 2002. J Vet Intern Med. 16:457-463.
The role of circulating platelets to arrest blood loss when vascular damage has occurred involves adhesion of the platelets to the exposed subendothelial collagen; platelet aggregation; formation of a platelet plug; and release of prothrombotic and vasoconstrictor substances. Platelet aggregation and clot formation can be detrimental in a number of disease processes and omega-3 fatty acid supplementation may decrease platelet aggregation in response to inflammation. Horses, along with all other mammalian species, have a dietary requirement for the essential omega-3 (n-3) and omega-6 (n-6) fatty acids. There exists a species-specific effect with respect to n-3 fatty acid requirements. Humans and dogs require absolute amounts for platelet aggregation whereas the n-6: n-3 ratio appears to be at least as important as the absolute amounts of n-3 fatty acids in rats. In horses, the effects of these fatty acids on platelet activation or aggregation or for the attenuation of leukocyte activation and chemotaxis are unknown. Thus, the present study examines the plasma concentration of various fatty acids – linoleic acid (LA), alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) – and platelet aggregation in healthy, adult horses after dietary supplementation of flaxseed oil, a source of ALA. Twelve mature female horses were fed a control diet or a control diet containing 10% flax seed oil. Total n-6:n-3 ratios were identical (1:2.1) Horses fed flax seed oil had higher LA, ALA and EPA levels, and a higher n-3:n-6 ratio. No decreases in AA were observed but this may be due to the linoleic acid in flax seed oil. Malondialdehyde (MDA) is produced after lipid peroxidation, and is an indicator of oxidative damage, and of disease. MDA was increased in flax seed-supplemented group, which may indicate the increased requirement for antioxidants. Behavioral differences were noted in that the group supplemented with flax seed oil did not exhibit signs of wood chewing whereas the control group exhibited persistent wood chewing. Human data has previously shown that DHA-supplementation decreases aggressive behavior. A dose-dependent effect on MDA and on behavior modification was possibly demonstrated in this study, given the similarity in the n-3:n-6 ratio between the two study groups. No change in platelet aggregation was seen between study groups, which may be due to the limited biologic effect in healthy subjects or to the inability of flax seed to induce the necessary biochemical effect of replacing n-6 fatty acids with n-3 fatty acids.