Eating black soya beans could lower fat and cholesterol levels and may help prevent diabetes, a study suggests.
Yellow soya is already known to lower cholesterol, but black soya is used in traditional oriental medicine as a treatment for diabetes.
The Korean study found rats who got 10% of their energy from black soya gained half the weight of those who had none, Chemistry and Industry reports.
UK diabetes experts warned black soya alone would not prevent the condition. In the study, also reported in the Journal of the Science of Food and Agriculture, the researchers from Hanyang University, Seoul, fed 32 rats a high-fat diet.
The animals were divided into four groups. One group was given no black soya protein while the other groups derived either two, six or 10% of their energy from the food.
After 28 days, it was found that the animals which ate the most black soya had gained half as much weight as those who had had none.
The group who had eaten most black soya also levels of total blood cholesterol that were 25% lower and of LDL "bad" cholesterol that were 60% lower than those who ate none.
The researchers, led by Shin Joung Rho, said the study showed that eating black soya prevented weight gain and improved cholesterol levels, but did not suggest why the food might have the effects.