Effects of fresh and heated soy oil on plasma heme oxygenase level in rats. Shown are the changes in heme oxygenase level in rats fed with basal diet (control), fresh soy oil (FSO), soy oil heated once (1HSO), soy oil heated twice (2HSO), soy oil heated five times (5HSO) or soy oil heated ten times (10HSO). The results are expressed as percentage based on baseline values. Data are expressed as means ± S.E.M. (n = 7), p < 0.05 indicates significant difference compared to acontrol, bFSO group.