Submitted to: Journal of Federation of American Societies for Experimental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 2/15/2005
Publication Date: 3/4/2005
Citation: Stewart, B., Ferguson, M., Badger, T.M., Nagarajan, S. 2005. Dietary soy protein isolate (SPI+) inhibits development of atherogenesis in familial hypercholesterolemic mouse model. Journal of Federation of American Societies for Experimental Biology. 19(5):A1460.
Interpretive Summary: Asian populations who consume diets high in soy have lower cardiovascular disease than those who do not eat soy foods. In the United States, more than 1 million infants a year are fed soy-based formula. There are several cardiovascular diseases in children and we are interested in determining if soy can reduce the incidence of those diseases. In this study, we found that mice bred to develop atherosclerosis had fewer lesions in the aorta than rats fed the control diets made with casein. These data appear to confirm those in people who consume soy. Furthermore, this study demonstrated that the protective effects were due to the protein itself and not to the phytochemicals, like isoflavones, that are bound to the protein. Further research will determine the mechanisms.
Technical Abstract: We previously reported that dietary intake of soy protein isolate (SPI) or isoflavone-free soy protein isolate (SPI-) reduced the onset and incidence of breast cancer in rats. In this study, the protective effects of SPI diets on the development of atherogenesis were studied using a familial hypercholesterolemia mouse model. Apoprotein E knockout female (apoE-/-, 28 day old) mice were fed AIN-93G diets (with normal cholesterol and lipid levels) formulated with Casein (control) or SPI+ or SPI- as their sole protein source for 126 days. The growth rate, food intake and body weight gains were not different between animals fed casein or SPI+ or SPI- diets. Similarly the cholesterol levels prior to the start of the study were abut 265 mg/dL and did not differ significantly after 72 days of feeding the three diets. Despite not affecting serum lipid profiles, both SPI+ and SPI- suppressed the lesions in descending aorta (SPI+ p=<0.001; SPI- p<0.02). The findings from this study show that soy-based diets decrease the development of atherogenesis in this familial hypercholesterolemia mouse model. Furthermore, it appears that the soy protein or a peptide produced upon digestion (rather than soy phytochemicals) plays an important mechanistic role in prevention atherogenesis.