The effects of oral fat ingestion on plasma concentrations of lipids, lipoproteins and apolipoproteins were studied in fasted 8 healthy men aged 25-43 years (mean age: 30 years old). Any one of cream 200g (49% fat), butter 100g (81% fat) or margarine 100g (81.6% fat) was ingested within 10 minutes early in the morning on three different days. Blood was withdrawn at 0, 60, 120, 180, 240 and 300 minutes after fat ingestion. Lipoproteins were fractionated by sequential ultracentrifugation. Apolipoproteins were measured by single radial immunodiffusion. Fasting plasma concentrations of lipids and apolipoproteins were as follows: Cholesterol (Ch); 190.9±9.6mg/dl, triglyceride (TG); 104.4±12.8mg/dl, phospholipids (PL); 193.6±5.9mg/dl, HDL-Ch; 64.1±2.9mg/dl, apo A-I; 145.0±2.6mg/dl, apo A-II; 32.2±0.7mg/dl, apo B; 75.3±5.9mg/dl, apo C-II; 3.1±0.3mg/dl, apo C-III; 7.7±0.5mg/dl, apo E; 4.1±0.2mg/dl. After each fat ingestion, plasma TG increased mainly due to the increments of VLDL- and chylomicron (d<1.006g/ml)-TG and IDL (1.006<d<1.019g/ml)-TG. There was no significant dif-ference between response of plasma TG after butter load and that of margarine. Plasma Ch increased due to VLDL-Ch and no significant changes of the Ch concentrations in the other lipoprotein fractions were observed. Miyajima et al reported that margarine load for 4 weeks decreased plasma Ch, LDL-Ch and HDL-Ch, while butter load increased LDL-Ch and decreased HDL-Ch. Long term effects of butter or margarine were not reflected in the acute effects of butter or margarine load observed in the present study. Degree of plasma lipids (especially TG) response to fat ingestion varied from subjects to subjects. Increment of plasma TG concentration after fat ingestion correlated significantly to fasting plasma levels of TG: cream (r=0.90, p<0.001), butter (r=0.89, p<0.005) and margarine (r=0.71, p<0.05). The data indicated that degree of TG increase after fat load is partly reflected in the fasting plasma levels of lipids.
