Journal Name:
J. Nutr.
Article Title:
Stearic, oleic, and linoleic acids have comparable effects on markers of thrombotic tendency in healthy human subjects.
Date Written:
2005
Volume:
135
Number:
12
Page:
2805
Author(s):
Thijssen, M. A.; Hornstra, G.; Mensink, R. P.
Article:
The most common complications of cardiovascular disease result from the formation of an arterial thrombus which is initiated by problems in the hemostatic balance. The thrombotic tendency of the blood is influenced by total fat intake and the fatty acid composition of the diet. Dietary fatty acids can change the fatty acid composition of platelets and other cell membranes, thus altering the availability of the pro-thrombotic prescursor, n-6 arachidonic acid (AA). Arterial thrombosis has been shown to be decreased by (n-6) and (n-3) polyunsaturated fatty acids (PUFA), whereas saturated (SFA) with 12–16 carbon atoms enhance formation. The effects of oleic acid, a monounsaturated fatty acid (MUFA) have been shown to be neutral and in some cases, antithrombotic compared with SFA. The SFA, stearic acid (C18:0) has been reported not to affect arterial thrombosis tendency, as well as in animal models to be highly thrombogenic. Overall the data for the data for stearic acid, oleic acid and linoleic acid appear to be is inconsistent. The objective of the present study was to compare the effects of stearic, oleic, and linoleic acids on platelet aggregation, coagulation, fibrinolysis, and hematological variables.
In this randomized, crossover study, 45 subjects (27 women and 18 men) consumed, in random order, 3 experimental diets, each for 5 week. Diets contained ~38% of energy as fat. Dietary compositions were the same except for 7% of energy from stearic, oleic, or linoleic acids. At the end of each period, ex vivo and in vitro platelet aggregation, and variables of coagulation, fibrinolysis, and hematology were evaluated. In men, ex vivo platelet aggregation time as measured by filtragometry was favorably prolonged during consumption of the linoleic acid diet compared with the stearic acid diet, but there was no difference with consumption of the oleic acid diet. A prolonged aggregation time indicates lower in vivo platelet aggregability and is negatively associated with mortality from coronary heart disease. The findings of this study indicate a gender-dependent effect of dietary fatty acid intake on ex vivo platelet aggregation. Whether other saturated fatty acids would have given similar effects remains to be clarified.
Stearic acid, oleic acid, and linoleic acid did not differ in their effects on in vitro whole-blood platelet aggregation variables induced by either ADP or collagen and did not differ in their effects on factor VIIam activity. In vitro platelet aggregation induced by collagen and ADP, and variables of coagulation (factor VII amidolytic activity and concentrations of fibrinogen and prothrombin fragment 1 and 2) and fibrinolysis [plasminogen activator inhibitor (PAI) activity and concentrations of tissue plasminogen activator (tPA)/PAI-1 complexes] did not differ among the 3 diets. Concentrations of fibrinogen and PA1 are positively associated with the risk of coronary heart disease. As markers of fibrinolytic activity, concentrations of tPA and PAI-1 antigen, tPA and PAI activities, and concentrations of tPA-PAI-1 complexes are also related to the risk of coronary heart disease. Various earlier studies evaluated the effects of dietary fatty acid composition on variables of the fibrinolytic system. In this study, stearic, oleic and linoleic acid consumption did not affect PAI activity and concentrations of tPA/PAI-1 complexes, which are strongly correlated with plasma levels of PAI activity or tPA antigen.
In both men and women, platelet volume was decreased after consumption of the diet high in stearic acid. Previous research has shown that stearic acid enriched diets also decrease platelet volume compared with diets rich in palmitic acid. Larger platelets are associated with increased platelet reactivity and risk of myocardial infarction. In this study, the mean platelet volume of the subjects decreased during consumption of the stearic acid diet by 0.32 fL compared with the oleic acid diet and by 0.35 fL compared with the linoleic acid diet.
In conclusion, these results do not suggest that stearic acid is highly thrombogenic compared with oleic and linoleic acids. Compared with the stearic acid diet, the diet high in linoleic acid decreased ex vivo platelet aggregation in men only. Stearic acid decreased platelet volume relative to both other fatty acids in both men and women. Effects on coagulation and fibrinolytic variables did not differ after consumption of the 3 fatty acids. Stearic acid consumption reduced platelet volume relative to the other 2 fatty acids, whereas effects on coagulation and fibrinolytic variables did not differ among the 3 fatty acids. Since canola oil is very low in stearic, high in oleic and moderate in linoleic, these results suggest that consumption of this oil would favorably reduce thrombogenesis.
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