State of Science :: Nutritional Quality
Scientists Identify Key Lipid-Lowering Ingredient in Soybeans
It has been known for years that the consumption of soybeans improves cardiovascular health by helping to remove LDL (bad) cholesterol from the blood stream. An intensive search has been underway for the active agent in soybeans responsible for this benefit, in the hope that it might prove useful as a nutraceutical or dietary supplement. A team of Italian scientists has now identified the active protein molecule in soybeans that lowers blood lipid levels and have labeled it the alpha-prime subunit of the soybean 7S globulin. (A globulin is a polypeptide chain that is folded like a globe, and is water insoluble). They also have discovered the mechanism through which it accomplishes this beneficial outcome.
This alpha-prime polypeptide subunit is one of three that make up the soybean 7S globulin. It constitutes about 35 percent of the 7S globulin. It works by upregulating the Beta-VLDL receptor in the liver, in effect stimulating the liver to more aggressively latch onto and metabolize LDL cholesterol in the blood supply. The authors highlight one aspect of their findings -
"The results of the present study, in our opinion, are extremely intriguing because they show for the first time that a dietary protein is active at concentrations that are lower than those reported for hypolipidemic drugs."
Given that this biologically active protein has just been isolated, no work has been done on the impact of genetics and farming systems on its levels in soybeans, nor on the impact of food processing and food preparation. The Organic Center will continue to monitor research in this area to see if there are ways to increase the concentration of this key protein.
Source: "The Alpha-Prime Subunit from Soybean 7S Globulin Lowers Plasma Lipids and Upregulates Liver Beta-VLDL Receptors in Rats Fed a Hypercholesterolemic Diet"
Authors: Marcello Duranti, Maria Rosa Lovati, Valeria Dani, Alberto Barbiroli, Alessio Scarafoni, Silvia Castiglioni, Cesare Ponzone, and Paolo Morazzoni, University of Milan, Italy
Journal: The Journal of Nutrition, Volume 134, No. 6, June 2004