Anthocyanin Rich-Black Soybean Testa Improved Visceral Fat and Plasma Lipid Profiles in Overweight/Obese Korean Adults: A Randomized Controlled Trial

Anthocyanin-rich black soybeans have been used in traditional East Asian medicine to cure diseases related to oxidative stress and carcinogens, but not obesity. Our objective was to investigate the effects of anthocyanin-rich black soybean testa extracts (BBT), Glycine max (Chongja No. 3), on obesity. In total, 63 participants defined as overweight or obese by their body mass index (BMI >23) or waist circumference (WC >90 cm for males, >85 cm for females) were sorted into two groups: 32 receiving the trial medication (BBT, 2.5 g/d) and 31 receiving the placebo (starch, 2.5 g/d). Participants completed an 8-week, randomized, double-blinded, and placebo-controlled clinical trial. There were no significant differences between the two groups at the beginning of the trial, and both required the same safety assessments. Significant decreases in abdominal fat, described according to WC and hip circumference, and lipid profiles such as triacylglycerols (TG), low density lipoprotein cholesterol (LDLc), and non-high density lipoprotein cholesterol (non-HDLc) were observed in the BBT group at the conclusion of the clinical trial. The indicators for arteriosclerosis such as total cholesterol (TC)/HDLc and LDLc/HDLc were significantly decreased in the BBT group, but had not changed in the placebo group. With no difference between the two groups in energy-adjusted dietary intakes and physical activity, BBT was shown to strongly improve plasma lipid profiles, related to the reduction of WC (an indicator of abdominal fat) as long as high dietary fiber and low cholesterol diets were maintained. In conclusion, BBT can potentially be developed as a functional food for preventing abdominal obesity with high fiber and low cholesterol diets.