Recent studies have suggested that omega 3-fats of marine origin may have a protective role in heart disease. This study aimed to compare the effects of fish or fish oil, in the setting of a high- or low-fat diet, on platelet aggregation and platelet thromboxane in men with increased risk of cardiovascular disease. One hundred twenty men who were nonsmokers, 30 to 60 years old, with mildly elevated blood pressure and cholesterol were randomly allocated to one of five high-fat (40% of daily energy) or two low-fat (30%) groups for 12 weeks. The five high-fat groups took either 6 or 12 fish oil capsules daily; fish; a combination of fish and fish oil; or placebo capsules. The two low-fat groups took either fish or placebo capsules. Fish meals provided 1.3 g of eicosapentaenoic acid daily, equivalent to 6 fish oil capsules, and contained an average of 3.65 g/d of omega 3-fatty acids. Multiple regression analysis of the combined groups showed that all groups taking omega 3-fatty acids reduced platelet aggregation to both collagen (P < .0001) and platelet-activating factor (PAF) (P < .05) and platelet thromboxane B2 responses (P < .05) to collagen-induced aggregation. The low-fat diet alone had no effect on PAF-induced platelet aggregation and only a small effect on platelet responses to collagen (P < .05). Platelet aggregation responses to PAF were reduced more by fish oil than fish in a high-fat diet, whereas fish had a greater effect when part of a low-fat rather than a high-fat diet. There was no significant difference in collagen-induced platelet aggregation or platelet thromboxane between fish and fish oils on a high or low fat intake. In conjunction with our previous findings of improvements in lipoproteins, blood pressure, and heart rate in this population, these results on platelet function suggest that dietary omega 3-fatty acids incorporated into a low- rather than a high-fat diet have a wider spectrum of more favorable effects on cardiovascular risk factors.

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1. This study was designed to seek evidence for excessive lipid peroxidation in pre-eclamptic women using 8-iso-prostane as a novel bioactive marker of lipid peroxidation in vivo. Plasma free, total and urinary 8-iso-prostane were measured in 20 women with proteinuric pre-eclampsia, and compared with 18 age- and gestation-matched pregnant control subjects, before delivery and at 6 weeks post-partum. 2. Plasma free 8-iso-prostane was significantly elevated in the pre-eclamptic women compared with control subjects before delivery, and fell to control levels post-partum. Conversely, levels in women with normal pregnancy rose post-partum. 3. Total plasma 8-iso-prostane levels were not significantly elevated in pre-eclamptic women compared with control subjects during pregnancy, but fell significantly in the pre-eclamptic women post-partum, suggesting that they had relatively higher levels compared with their non-pregnant state. 4. Urinary 8-iso-prostane excretion was significantly lower in the pre-eclamptic women compared with control subjects during pregnancy, suggesting that renal clearance of 8-iso-prostane is impaired in pre-eclampsia. 5. Increased levels of plasma free 8-iso-prostane in pre-eclampsia could be due to an increase in lipid peroxidation, an increase in phospholipase A2 activity or a reduction in renal clearance of 8-iso-prostane, or a combination of all three. The potent direct and indirect vasoconstrictor actions of 8-iso-prostane may contribute to the pathogenesis of pre-eclampsia.

The results suggest that, in GDM, increased severity of insulin resistance and related features of the 'metabolic syndrome', rather than lipid abnormalities, are precursors to the development of pre-eclampsia and hence are likely to be implicated in the pathophysiology of this disorder. Moreover, these women are likely to be at particularly high risk of long-term cardiovascular disease and Type 2 diabetes.