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Food Lipids: Chemistry, Nutrition, and Biotechnology

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Figure 13 Schematic representation of platelet activation. Arachidonic acid from platelet<br />

acts as a substrate for thromboxane A 2 (TxA 2) <strong>and</strong> arachidonic acid from the endothelial cells<br />

for prostacycline (PGI 2). The balance between these two eicosanoids affects platelet activation.<br />

TxB 2 is the stable metabolite of TxA 2, <strong>and</strong> 6-keto-PGF 1� of PGI 2.<br />

2. Platelet Aggregation <strong>and</strong> Coronary Heart Disease<br />

In vitro platelet aggregation has been reported to be an important marker for the<br />

prediction of reoccurrence of coronary events [62]. In addition, platelet aggregation<br />

measured in whole blood was strongly associated with the prevalence of ischemic<br />

heart disease [63].<br />

3. Dietary Fats <strong>and</strong> Platelet Aggregation<br />

a. Total Fat Content of Diets. Renaud <strong>and</strong> coworkers [64] studied nine groups<br />

of farmers from different areas in France <strong>and</strong> Britain, who differed with respect to<br />

dietary intakes of total <strong>and</strong> saturated fatty acids. In the groups with a high consumption<br />

of total <strong>and</strong> saturated fatty acids, an increased thrombin-induced aggregation<br />

in platelet-rich plasma was observed as compared with the groups of farmers<br />

with lower intakes. In a later intervention study [65], the diets of French farmers<br />

were reduced in saturated fat content by replacing the habitually consumed dairy fat<br />

by a high linoleic acid margarine. A control group of farmers was advised not to<br />

change their diets. In the intervention group, total fat intake decreased along with<br />

the intake from saturated fatty acids, whereas the intake of dietary linoleic acid <strong>and</strong><br />

�-linolenic acid was increased compared with initial values. In agreement with the<br />

previous study [64], a decreased thrombin-induced aggregation was observed in the<br />

intervention group, whereas platelet aggregation did not change in the control group.<br />

However, platelet aggregation induced by ADP was significantly increased in the<br />

intervention group. From this dietary intervention, however, it was not clear whether<br />

the changes of total fat content or the changed fatty acid composition of the diets<br />

were responsible for the changes observed in platelet aggregation.<br />

b. Dietary Fatty Acid Composition. The effects of dietary fatty acid composition<br />

were further evaluated in well-controlled dietary intervention studies, in which<br />

total fat content of the diets was kept constant <strong>and</strong> only the dietary fatty acid composition<br />

changed.<br />

Mutanen et al. [66] observed increased ADP- <strong>and</strong> collagen-induced aggregation<br />

in platelet-rich plasma after consumption of diets rich in sunflower or rapeseed oils<br />

Copyright 2002 by Marcel Dekker, Inc. All Rights Reserved.

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