Black soybeans more effective than yellow at cutting cholesterol
soybeans, report Japanese chemists who studied the antioxidant
power in the two varieties.
Several studies have demonstrated that the daily intakes of soy foods benefits heart health, likely through the plant's effect on cholesterol levels.
But the new research suggests that some varieties may have a more important effect than others.
A team from Ochanomizu University in Tokyo extracted antioxidants and anthocyanins from seed tissue. They measured LDL oxidizability by introducing an oxidizing agent and different soybean extracts to isolated LDL samples.
Oxidization of LDL leads to fatty substances and cholesterol building up inside artery walls, increasing risk of stroke in people.
The diluted extract solution from the black soybean seed coat prolonged LDL oxidation lag time significantly more than the original extract of the yellow soybean seed coat, report researchers in the June issue of the Journal of Agricultural Food and Chemistry 1;53(11):4578-82.
The researchers also show that antioxidant capacity comes primarily from the black soybean seed coat. The seed coat of black soybean had a higher polyphenol (isoflavones and anthocyanins) content that that of yellow soybean, 29.0 vs. 0.45 mg/g respectively.
Isoflavones and anthocyanins are believed to act as antioxidants.
