Researchers from Korea have reported that peptides from black soy bean could help in combating obesity. A study on rats showed that this bean curbed weight gain.
Soy proteins and soy peptides have received attention for their hypolipidaemic and hypocholesterolaemic properties, as well as their ability to lower blood pressure, improve arterial compliance and endothelial function, insulin resistance and weight loss in obesity.
However, most of the studies have been conducted using yellow soy, which is a fixture of Western diets. Black soy is a component of oriental medicine for diabetes and a variety of other indications, but the researchers propose that it could play a greater role in efforts to curb the obesity crisis in the West.
How the research was done
The scientists from the Department of Food and Nutrition at Hanyang Universityled by Hyeon Gyu Lee, set out to assess the effect of black soy peptide supplementation on weight gain and lipid composition in rats that were fed a high-fat, high-cholesterol diet for 28 days.
The 32 Sprague-Dawley rats were divided into four groups. Three groups received black soy peptide (BSP) making up two, six or ten percent of energy respectively, and the control group received casein making up 20 percent of energy.
At the end of the 28 days, weight gains in body, liver and epidermal adipose tissue of the the BSP rats was seen to be significantly attenuated compared to the casein rats, and the effect was seen to be connected to BSP concentration.
The BSP rats also had lower total cholesterol, lower LDL/HDL serum concentrations, lower levels of hepatic triglycerides and increased faecal excretion.
Modulation of lipid composition
"Our results suggest that BSP may be a bioactive source of anti-obesity through modulation of lipid composition which might contribute to the amelioration of obesity-related metabolic diseases such as atherosclerosis, cardiovascular disease and diabetes," wrote the researchers.
However, they said there is a need for additional studies on the long-term effects of BSP consumption and competitive confirmatory studies with yellow soy beans – in particular since their study looked only at weight gain and lipid composition.
Over 300m adults are obese worldwide, according to the latest statistics from the WHO and the International Obesity Task Force.
But not everyone is convinced that black soy could join the ranks of commercialised anti-obesity ingredients.
Professor David Bender from the Royal Free and University College Medical College in London told Chemistry & Industry magazine that he was sceptical: If food intake is greater than energy expenditure, then the excess will have to be stored somehow, and that will be storage as fat – even if the black soya is inhibiting fatty acid synthesis to some extent." - (Decision News Media, February 2007)
Soy & Health