Dietary Fats and Platelet Function among Finnish Men

Abstract

The aim of this study was to elucidate the role of platelet aggregation as a risk factor for ischemic heart disease (IHD) and the relationship between fatty acids and platelet function. Platelet aggregation upon adenosine diphosphate (ADP), adrenaline and thrombin were measured in middle aged men in east and west, two regions of Finland with a nearly twofold difference in IHD mortality. Platelet aggregation results were correlated with the fatty acid compositions of plasma lipid fractions, adipose tissue triglycerides and platelet phospholipids.

There was no significant east-west difference in platelet reactivity to ADP, adrenaline and thrombin. ADP-induced platelet aggregation showed significant negative correlations with all the platelet C20-C22 n-3 polyunsaturated fatty acids (PL)FA), but significant positive correlations with the percentage of 18:2n-6 in adipose tissue and plasma cholesterol esters (CE) and triglycerides (TG). Adrenaline-induced aggregation correlated negatively with the percentage of 20:5n-3 in plasma CE and TG, and positively with the total percentage of saturated fatty acids in platelets. Aggregation upon thrombin had a negative correlation with the 20:3n-6/20:4n-6 ratio in plasma CE and a positive correlation with 18: 2n-6 in adipose tissue.

The percentages of the major PUFA in platelets correlated sgnificantly with the same fatty acids in plasma CE and phospholipids PL. Platelet 20: 5n-3 had a highly significant negative correlation with the percentage of 18:2n-6 in plasma and adipose tissue lipids. Platelet 20: 4n-6 was unrelated to its precursors in plasma. The percentage of 18: 2n-6 in plasma and adipose tissue lipids was consistently lower in men from eastern than western Finland, whereas the percentage of platelet 20: 5n-3 was higher in the eastern men.

The results indicate, that (1) platelet function may not play a role in the regional gradient in IHD rate in Finland, (2) in a free-living population, relatively small changes in plasma and platelet fatty acids may have significant influence on platelet aggregation and on thrombosis tendency and (3) an increase in dietary PUFA content may not affect platelet function favourably, unless attention is paid to the maintaining of the n-3/n-6 ratio in the diet.

Key Words:

• platelet aggregation
• fatty acids
• linoleic acid
• archidonic acid
• eicosapen-taenoic acid