EFFECTS OF SOY PROTEIN ISOLATE (SPI) AND CASEIN ON THE POSTPRANDIAL LIPEMIA IN NORMOLIPIDEMIC MEN

To elucidate the effects of soybean protein and casein on postprandial lipemia, oral fat load tests were performed before and 3 weeks after the administration of soy protein isolate (SPI) and casein supplement to normolipidemic men. Eleven normolipidemic male subjects on otherwis e identical controlled diets were assigned to either a 20 g/d soy prot ein isolate (SPI) dietary supplement or a casein dietary supplement fo r three weeks in a crossover design. Fat load tests with 40 g/m(2) of bovine milk fat were carried out before and after 3 weeks on the exper imental dietary supplements. Fasting plasma concentrations of lipids a nd apolipoproteins were not significantly different from baseline leve ls before or after the administration of SPI or casein supplemented di ets. Neither SPI nor casein supplement affected the fasting plasma con centrations of lipids and apolipoproteins. The areas under the increme ntal curve (AUIC) of triglyceride (TG) and remnant-like particles trig lyceride (RLP-TG) after both experimental diets were not significantly different from those before the experimental diets. However, the AUIC of remnant-like particles cholesterol (RLP-C) showed a tendency (p = 0.07) to decrease after administration of the diet supplemented with S PI than before the diet. The AUIC of RLP-C was significantly (p < 0.05 ) lower after the diet supplemented with SPI than after administration of the diet supplemented with casein. These results suggest that 3 we eks of 20 g/d SPI dietary supplement favorably affects the postprandia l remnant lipoprotein response as compared to the casein dietary suppl ement.