Influence of dietary fat mixtures on platelet adhesiveness, atherosclerosis and plasma cholesterol content in rabbits

Abstract

Summary Platelet adhesiveness, degree of atherosclerosis and plasma cholesterol content were examined in rabbits fed for 62 weeks a diet deficient in essential fatty acids (EFA) containing 40 cal % hardened coconut oil, or diets in which 10 cal % of the hardened coconut oil had been replaced by linseed oil (rich in linolenic acid) or by safflower oil (rich in linoleic acid). Additionally, histopathological and clinical investigations, were carried out to gain some information about the consequences of feeding rabbits a diet deficient in EFA for a prolonged period. The results are: (1) The three dietary groups showed no significant differences as to platelet adhesiveness to glass. (2) Atherosclerosis of the aorta was more severe in the hardened coconut oil group (Mean Atheroma Index = 2.33) than in the linseed oil group (m.a.i. = 1.00) or the safflower oil group (m.a.i. = 0.25). The frequency of coronary artery changes was also significantly higher in the hardened coconut oil group than in the two other groups. One animal of the hardened coconut oil group showed a myocardial infarction. (3) The plasma cholesterol content was significantly higher in the hardened coconut oil group than in the two other groups. (4) All but one animal of the hardened coconut oil group showed a cirrhotic liver, whereas the animals of the other two groups displayed hardly any liver changes. (5) Haemolysis time in isotonic thiourea solutions showed significant differences between all dietary groups of rabbits. The hardened coconut oil group showed the shortest time; the safflower oil group the longest. A positive correlation was found between haemolysis time and the polyunsaturated fatty acids content of the erythrocytes. Since their saturated fatty acid content was fairly constant, a negative correlation also existed between the haemolysis time and the monounsaturated fatty acid content. However, this correlation was not found within every dietary group since either the number of individual values is insufficient or the correlation is spurious. The conclusion is drawn that linseed oil has no specially favourable effect on platelet adhesiveness or atherosclerosis. With regard to the latter aspect, safflower oil is preferable.