Diurnal changes in plasma apoprotein levels were measured in 6 healthy volunteers. The same meal was given on two consecutive days and 30gr of fat (P/S ratio: 1.2) was administered with each meal on the second day. Blood samples were taken at fasting, at 1 and 3 hours after breakfast, at 2 and 4 hours after lunch and supper. Plasma total cholesterol, triglyceride, HDL-cholesterol and apoprotein A_I A_II, B, C_II, E levels were measured. Plasma apoprotein levels were measured with the method of single radial immunodiffusion (SRID).
Plasma triglyceride levels reached the peak at 2 hours after lunch and declined slightly afterwards. Fat administration increased the postprandial triglyceride levels but had no effects on the curve of the diurnal change. Plasma total cholesterol and HDL-cholesterol levels did not show any diurnal changes and were not affected by oral fat administration. The levels of plasma apoprotein A_I, A_II, B, C_II, E did not show any diurnal changes and were not influenced by oral fat administration. Therefore, the postprandial levels of total cholesterol, HDL-cholesterol and apoproteins can be considered as the same values as the fasting values.