Blood and Aorta Lipid Status and Platelet Function in Swine Modified by Dietary Alpha -Linolenic Acid-Rich Flaxseed.
Blood and Aorta Lipid Status and Platelet Function in Swine Modified by Dietary Alpha -Linolenic Acid-Rich Flaxseed.
Year: 1996
Authors: G Cherian, D U Ahn, J S Sim.
Publication Name: J. Agric. Food Chem.
Publication Details: Volume 44; Page 2330.
Abstract:
The majority of research on the anti-thrombotic properties of n-3 PUFAs has focused upon EPA from fish oils because it is the direct precursor of eicosanoids which reduce platelet clotting. Recently, interest has grown regarding the role that dietary ALA can play in increasing cellular EPA concentrations and decreasing the synthesis of AA from LA. The objective of the present study was to examine different levels of dietary ALA for effects on AA:EPA ratios in the blood and in various tissues. Swine were fed varying levels of ALA to assess effects on FA composition of plasma, red blood cells, aorta, platelets, plasma cholesterol, TGs, and platelet response to collagen-induced aggregation. Pigs were used in this investigation as a model for lipid metabolism in humans. Twenty-five pigs were fed diets containing no ALA (control) or flaxseed at various levels equivalent to 1.5% (ALA1), 2.5% (ALA2) and 3.6% (ALA3). Diets were fed for a period of 4 months. The data indicated that ALA supplementation resulted in a significant enrichment of ALA and EPA in plasma, red blood cells, aorta, platelet neutral, and PLs with a concomitant significant reduction in AA. These changes resulted in a decrease in the AA:EPA ratio which would have the effect of reducing the synthesis of pro-inflammatory and pro-thrombotic eicosanoids. No changes were noted in plasma TC concentration or in DHA levels in any of the tissues examined. Plasma TG concentrations were reduced significantly in pigs receiving all ALA treatments in comparison to pigs receiving the control diet. Platelet aggregation induced by collagen was significantly higher in the control group when compared with ALA2 and ALA3 diets, respectively. The authors indicated that their data clearly establishes the effectiveness of dietary ALA to serve as a source of EPA in plasma and red blood cell total lipids. The lack of increase in DHA suggests that the conversion of ALA to DHA may be limited in swine or that a longer dietary period is required to increase DHA levels. The reduction in plasma TG noted in this study is consistent with research findings in humans. It has been postulated that n-3 PUFAs affect the enzymes involved in hepatic TG synthesis, thus reducing the pool of FAs available for the synthesis of TG and VLDL secretion. N-3 PUFAs may also enhance beta-oxidation of FAs in the liver. The results also suggest that an increase in ALA and a decrease in the AA:EPA ratio in platelets reduces the tendency of platelets to aggregate. This effect is most likely due to alterations in eicosanoid synthesis and activity. The authors conclude that the long-term use of moderate amounts of oils containing ALA such as flaxseed oil as well as ALA-enriched animal products could lead to significant changes in blood and aortic tissue EPA and ALA concentrations and reductions in coronary heart disease risk.
