Soy in Health and Disease: Perspectives
The first direct comparison of the atherogenic properties of animal protein and vegetable protein was made by D. R. Meeker and D. R. Kesten. They found a casein-based diet to be significantly more atherogenic for rabbits than one based on soy protein. Feeding of amino acid mixtures approximating the composition of casein or soy protein gave surprising results. The soy amino acid mixture raised cholesterol levels by 80%. Examination of the published data and of the composition of casein and soy protein raised the possibility that the lysine to arginine ratio may, in part, determine the atherogenic potential of a protein. The rabbits fed soy protein excreted 42% less feces than those fed a commercial diet but more than those fed casein. Substitution of soy protein for casein reduces cholesterol levels by 38% and Average atherosclerosis by 17%. When the fiber is alfalfa, serum cholesterol levels and atherosclerosis are significantly lower than levels in the cellulose group.