Partially hydrogenated soybean oil reduces postprandial t-PA activity compared with palm oil

The effects of dietary trans fatty acids on fasting and diurnal variation i n hemostatic variables are not known. This study compares the effects of th ree diets with three different margarines, one based on palm oil (PALM-diet ), one based on partially hydrogenated soybean oil (PHSO, TRANS-diet) and o ne with a high content of polyunsaturated fatty acids (PUFA-diet) on diurna l postprandial hemostatic variables. A strictly controlled dietary Latin sq uare study was performed and nine young female participants consumed each o f the diets for 17 days in a random order. The sum of the cholesterol-incre asing fatty acids (C12:0. C14:0. C16:0) was 36.3% of total fatty acids in t he PALM-diet, the same as the sum of saturated-(C12:0, C14:0, C16:0) (12.5% ) and trans fatty acids (23.1%) in the TRANS-diet. The sum of C12:0. C14:0 and C16:0 was 20.7% in the PUFA-diet. The amount of fat made up 30-31% of e nergy in all diets. Nine participants completed the study. The diurnal post prandial state level of tissue plasminogen activator (t-PA) activity was si gnificantly decreased on the TRANS-diet compared with the PALM-diet. t-PA a ctivity was also decreased on the PUFA-diet compared with PALM-diet but the difference was below statistical significance (P = 0.07. Bonferonni adjust ed). There were no significant differences in either fasting levels or in c ircadian variation of t-PA antigen, PAI-1 activity, PAI-antigen, factor VII coagulant activity or fibrinogen between the three diets. Our results indi cate that dietary trans fatty acids from PHSO has an unfavourable effect on postprandial t-PA activity and thus possibly on the fibrinolytic system co mpared with palm oil. (C) 2001 Elsevier Science Ireland Ltd. Ail rights res erved.