While there have been ample studies of a cross-cultural nature and experimental evaluations establishing the cardioprotective effect of soy protein, efforts to clarify the proportion of those benefits related to its phytoestrogen content are relatively recent. In most cases, the general approach to evaluating the role of soy's phytoestrogens has been to compare the cardiovascular benefits of isolated soy protein with a comparable soy protein isolate that has been alcohol extracted. Based on that approach, soy phytoestrogens appear to lower low-density lipoprotein concentrations while increasing plasma concentrations of the high-density lipoproteins. Particularly noteworthy with respect to the high-density lipoprotein effects are the increases in apolipoprotein A-1. Phytoestrogens may also prevent the oxidation of lipoprotein particles. The soy phytoestrogens favourably influence coronary artery reactivity. They also inhibit the progression of atherosclerosis in the coronary, iliac and common and internal carotid arteries. The cardiovascular benefits of soy phytoestrogens appear to be equal for males and females.