The Effects of Yellow Soybean, Black Soybean, and Sword Bean on Lipid Levels and Oxidative Stress in Ovariectomized Rats

Soy isoflavones have been reported to decrease the risk of atherosclerosis in postmenopausal women. However, the effects of dietary consumption of soybean have not been explored. In this study, we evaluated the effects of consuming yellow soybeans, black soybeans (Glycine max), or sword beans (Canavalia gladiate) on lipid and oxidative stress levels in an ovariectomized rat model. Forty-seven nine-week-old female rats were ovariectomized, randomly divided into four groups, and fed one of the following diets for 10 weeks: a diet supplemented with casein (NC, n = 12), a diet supplemented with yellow soybean (YS, n = 12), a diet supplemented with black soybean (BS, n = 12), or a diet supplemented with sword bean (SB, n = 11). Plasma triglyceride (TG) levels in the BS and SB groups were significantly lower than that in the NC group. Notably, the BS group had significantly lower plasma total cholesterol (TC), and low-density lipoprotein cholesterol (LDL-C) levels than the other groups. Hepatic total lipid levels were significantly lower in the YS and SB groups, and cholesterol levels were significantly lower in the SB group than in the NC group. Superoxide dismutase (SOD) and catalase (CAT) activities were significantly higher in the groups fed beans compared to the NC group. Hepatic thiobarbituric acid reactive substances (TBARS) levels were also significantly lower in the BS and SB groups than the NC group. In conclusion, our results suggest that consumption of various types of beans may inhibit oxidative stress in postmenopausal women by increasing antioxidant activity and improving lipid profiles. Notably, intake of black soybean resulted in the greatest improvement in risk factors associated with cardiovascular disease.