We determined the effects of soy protein isolate (SPI) intake on remnant-like particles (RLP), lipolytic enzymes, lipid transfer protein, transaminases, sex hormones, iron, calcium, and vitamin E in healthy men. In the first randomized, crossover experiment, 14 men were given either 20 g per day of SPI or nothing (control) for each 4-week segment. After 3 weeks of SPI intake, TG and RLP cholesterol levels were significantly lower than the baseline by 13.4% (p<0, 05) and 9.8% (p<0.05), respectively. However, no significant change was found in total and low-density lipoprotein (LDL) cholesterol levels or the activi-ties of lipoprotein lipase, hepatic lipase, cholesterol ester transfer protein, and lecithin cho-lesterol acyltransferase. Although the levels of transaminases, testosterone, iron, and cal-cium did not change, the vitamin E level was reduced from the baseline by 9.7%, a signifi-cant decrease (p<0.01). In the second study, we attempted to determine the effect of vita-min E supplement taken with SPI. For each 3-week segment, 12 men were given 20 g per day of SPI, either with or without 200 mg per day of vitamin E, in a randomized crossover design. The vitamin E level was reduced by 9.2%, a significant decrease (p<0.05), after SPI intake for 3 weeks, and vitamin E supplement increased vitamin E level significantly (p<0.05). These results demonstrate that SPI intake reduces remnant lipoproteins, TG, and the plasma level of vitamin E, although vitamin E supplementation compensates for the re-duction of vitamin E. Therefore the supplementation of vitamin E may be required in sub-jects with long-term and abundant intake of soy protein.