Journal Name:
Thrombosis & Haemostasis
Article Title:
Comparison of the effects of two diets rich in monounsaturated fatty acids differing in their linoleic/alpha-linolenic acid ratio on platelet aggregation.
Date Written:
1994
Volume:
71
Number:
1
Page:
73
Author(s):
Freese, R.; Mutanen, M.; Valsta, L. M.; Salminen, I.
Article:
In this investigation, the antithrombotic effects of α-linolenic acid (ALA) as well as the favorable effects of monounsaturated oleic acid in prevention of coronary heart disease were of interest. Low-erucic acid rapeseed oil or canola oil is rich in oleic acid (58% of total fatty acids) and contains also a substantial amount of ALA (11-13% of total fatty acids). In a cross-over study 20 healthy male subjects, average age 29 years (range 20 - 46 yr), followed experimental canola oil (CO) and a high –oleic Trisun-sunflower oil (TSO) diets after their habitual diet for six weeks. Subjects were provided most of the fat containing foods but were allowed to eat other foods almost freely. Fatty acid compositions of the diets calculated from dietary records were as follows (saturated/monounsaturated/ polyunsaturated fatty acids): CO diet 12.4/18.6/8.9% of total energy (en%) (omega 6 - linoleic/ALA ratio: 2.8) and TSO diet 11.8/17.8/8.3 en% (omega 6 -linoleic/ALA ratio: 28), respectively. The activity of antithrombin III (AT-III) in plasma was measured.
Platelet aggregations induced by ADP (1, 2 and 3 μM) or thrombin (0.12, 0.15 and 0.18 NIH/ml) were significantly enhanced and collagen- (1.5, 2.5 and 5.0 μg/ml) induced aggregation tended to be enhanced after the TSO diet compared with the CO diet. After the TSO diet platelet aggregation was enhanced from the level of the habitual diets by one thrombin (0.18 NIH/ml), one collagen (1.5 μg/ml) and all three ADP concentrations. The diets had no effect on antithrombin III activity.
The TSO diet induced stronger platelet response to all aggregating agents used than the CO diet, which indicates that different amounts or ratios of omega 6:omega 3 (linoleic/ALA) in diets rich in monounsaturated fatty acids have different effects on platelet function in vitro. In addition, platelet aggregation was significantly enhanced by all concentrations of ADP, the lowest dose of collagen (1.5 μg/ml) and the highest dose of thrombin (0.18 NIH/ml) after the TSO diet as compared with the pre-experimental level. No difference was, however, seen after the CO diet.
This study supports earlier research that showed that canola oil may be more effective in decreasing platelet aggregation or increasing bleeding time than sunflower or safflower oil (both of which contain high levels of omega fatty acids). An increase in ALA intake or a decrease in the ratio of omega 6/ALA in the diet appears to decrease platelet aggregation. Replacement of linoleic acid by ALA or the conversion of ALA to longer chain n-3 fatty acids, mainly eicosapentaenoic acid in platelet phospholipids, may be a partial explanation for reduced platelet aggregation following the canola oil diet.
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