Effects of Immature Soybeans on Lipid Metabolism in Rats Fed Normal and High-Fat High-Fructose NAFLD Diets

Edamame and chamame (brown edamame) are immature soybeans that contain abundant protein, vitamins, and dietary fiber. Edamame has a different nutrient composition compared with mature soybeans, as evidenced by its higher content of vitamins and folic acid. Recent studies have shown that proteins in mature soybeans, such as β-conglycinin, and dietary fiber influence the metabolism of lipids such as triglyceride and cholesterol. However, the effect of edamame on lipid metabolism has not been reported. In the present study, we investigated whether oral consumption of edamame or chamame affects lipid metabolism. We focused on the analysis of hepatic lipids, serum cholesterol, and fecal lipids in rats after feeding them a normal or non-alcoholic fatty liver disease (NAFLD) diet containing edamame or chamame for 6 wk. We found that the consumption of dietary edamame and chamame significantly lowered hepatic triglyceride and serum cholesterol levels compared with those in the control groups fed with normal and NAFLD diets. Intake of edamame and chamame improved the NAFLD-like fatty liver. Finally, intake of edamame and chamame resulted in a significantly higher amount of fecal lipids and bile acid than in the control, suggesting the stimulation of lipid excretion. Together, dietary edamame and chamame decrease hepatic and serum cholesterol by promoting lipid excretion, not by the regulation of hepatic gene expression, leading to the improvement of lipid metabolism in both normal and NAFLD model rats.