A new study
in rats reveals that a diet rich in black soya beans could help control weight, lower fat and cholesterol levels, and help in the prevention of diabetes.
Yellow soya beans already feature prominently in western diets, whereas black soya beans are more commonly associated with oriental medicine.
Previous laboratory studies suggest that the makeup of black soya beans should make them more potent than yellow soya beans at preventing cholesterol buildup.
Now a team of Korean researchers has shown that this is indeed the case, at least in rats, and that eating black soya also prevents weight gain
The mechanism of action of the black soya is unclear. But David Bender, sub-dean at the Royal Free and University College Medical School, London, thinks that the soya protein may be having an
effect on fat metabolism in the liver and adipose tissue, reducing synthesis of new fatty acids and cholesterol. (This differs from the action of obesity drugs such as Roche’s Xenical,
which simply inhibit absorption and digestion of dietary fat.)
It is this metabolic effect that may explain the traditional (oriental) use of black soya in the treatment of diabetes. ‘The key problem in type II diabetes is impairment of insulin
action, mainly as a result of excess abdominal adipose tissue – so loss of weight often improves glycaemic control,’ said Bender. But he still doubts whether black soya will be a
useful treatment for obesity. ‘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.’