Platelet aggregation in pigs fed diets containing anhydrous milkfat, fish oil or hydrogenated coconut oil

The purpose of the study was to measure platelet aggregation and fatty acid composition for pigs fed diets containing different fats/oils, and to compare platelet aggregation with empirical indices calculated from the fatty acid compositions of the diets and platelet phospholipids, and the index of thrombogenicity of Ulbricht and Southgate [1]. Four groups of 16 pigs were fed for 70 days on diets containing one of three test fats/oils; anhydrous milkfat (AMF), fish oil (MaxEPATM) or hydrogenated coconut oil (HCO) at a level of 100 g/kg, or a basal diet containing starch at the expense of the test fat/oil. Blood samples were collected from each pig at 56 and 70 days. ADP- and collagen-induced platelet aggregation were measured by the turbidometric method at 56 days, intra-platelet cGMP response to sodium nitroprusside activator was measured by radioimmunoassay at 56 days, and the fatty acid composition of platelet phospholipids was measured at 70 days. There was a significant effect of diet on collagen-induced platelet aggregation (%) (AMF 76.0, MaxEPA 70.8, HCO 81.3, basal 86.8) which was lower in the MaxEPA group compared to the hydrogenated coconut oil and basal groups, and on the proportions (% total fatty acids) of the major monounsaturated (18:1n-9, AMF 16.6, MaxEPA 13.1, HCO 14.6, basal 15.9; 18:1n-7, AMF 0.9, MaxEPA 3.3, HCO 1.1, basal 1.2) and polyunsaturated (18:2n-6, AMF 7.6, MaxEPA 7.4, HCO 8.7, basal 7.6; 20:4n-6, AMF 13.3, MaxEPA 4.8, HCO 16.2, basal 15.6; 20:5n-3, AMF 0.9, MaxEPA 10.3) fatty acids in platelet phospholipids. There were no significant effects of diet on ADP-induced platelet aggregation or platelet cGMP. The relative pattern of platelet aggregation across dietary treatments was consistent with empirical indices based on the ratios of the n-6/n-3 fatty acids in the diets and platelet phospholipids, but did not match the pattern based on the index of thrombogenicity [1]. The data suggest that useful factors for predicting platelet aggregation are the proportions of the fatty acids 18:2n-6 + 20:4n-6/18:3n-3 + 20:5n-3 + 22:6n-3 in the diets and platelet phospholipids.