Comparison of the Effects of Differently Processed Soy Foods on Lipid Metabolism in Rats

We investigated how different processing of soy foods impacts their hypolipidemic properties. Male rats were fed a diet containing 300 g/kg of roasted soybean, powdered soy milk, dried fresh tofu, or kori tofu for 21 days. Roasted soybean, a fiber-rich food, significantly increased the fecal total lipid content. The fecal excretion of bile acids was significantly stimulated by fresh tofu and kori tofu, both of which contain coagulated protein. Soy milk and tofu products, which are relatively rich in protein, partly suppressed hepatic lipogenesis compared to roasted soybean. Unfortunately, the impact of these differences was not apparent in reducing lipid levels in serum and liver. Given these observations, constant consumption of each soy food may modulate intestinal lipid absorption and hepatic lipogenesis differently.