Journal Name:
Lipids
Article Title:
Accumulation of eicosapentaenoic acid in plasma phospholipids of subjects fed canola oil.
Date Written:
1990
Volume:
25
Number:
NA
Page:
598
Author(s):
Bruce, V.M.; McDonald, .B.E
Article:
Platelet clotting or thrombogenesis is an important risk factor in coronary heart disease and is impacted by lipid metabolism and eicosanoid synthesis. An inverse relationship between the level of dietary omega-3 eicosapentaenoic acid (EPA) and a corresponding decrease in arachidonic acid (AA) in platelet phospholipids, with platelet clotting has been reported. There is controversy surrounding the relative importance of dietary alpha linolenic acid (ALA) in platelet function and its ability to increase the EPA content of plasma and platelet phospholipids. Many studies on the metabolism of ALA have been confounded by methodology and have not taken into account dietary concentrations of pertinent fatty acids. In addition, fatty acid composition often is reported for total plasma or platelet phospholipid as opposed to individual phospholipid species. Fatty acid composition varies among different phospholipids and the concentrations of the different species vary among tissues. Thus, it is possible that small but potentially important changes are masked when phospholipid species are not analyzed separately. *In this study, the conversion of alpha-linolenic acid (ALA) in canola oil to longer chain omega 3 fatty acids was studied in eight normolipidemic men. The design included a 42-day period divided into three: a 6-day pre-experimental and two 18-day experimental. Approximately 75% of the dietary fat (28% of total energy) was provided by a mixture of fats during the pre-experimental period and either canola oil (CO) or sunflower oil (SO) during the experimental periods. The CO and SO diets were fed in a cross-over design. The ratios of linoleic to linolenic acid were 2.6:1 and 73.9:1 in the CO and SO diets, respectively. Dietary fat source had an effect on plasma phospholipid fatty acids: oleic acid, ALA and EPA were significantly higher and AA was significantly lower in the phosphatidylcholine fraction; oleic acid was higher and AA was lower in the phosphatidylethanolamine fraction; and oleic acid and EPA were higher and AA and DHA were lower in the alkenylacyl ethanolamine phospholipid fraction on the CO diet as compared to the SO diet. *Consumption of the canola oil diet resulted in higher n-3 fatty acid levels and lower n-6 fatty acid levels in plasma phospholipids than consumption of the sunflower oil diet. The fatty acid composition of plasma phospholipid fractions showed important differences in response to dietary fat source which will have significant physiological impacts on health and disease risk. The increases in long chain omega 3 fatty acids in plasma phospholipid fractions could lead to beneficial reductions in thrombotic tendencies which could also result in lower risk of myocardial infarction. The authors attribute the compositional changes in the phospholipid fractions to the composition of the individual dietary fats. The canola diet contained less palmitic acid, stearic acid and LA, and more oleic acid and omega 3 ALA than the sunflower diet. The present study demonstrated that canola oil resulted in significant increases in the levels of EPA in plasma phospholipids.
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