A recently discovered bioactive peptide found in soybeans, lunasin is likely to be a key actor in soy's cholesterol-lowering actions. A study in which lunasin was added to human liver cells demonstrated the compound's potential to significantly lower cholesterol two ways -- by inhibiting the expression of the gene responsible for our body's internal production of cholesterol, while also increasing the expression of a gene that reduces levels of LDL cholesterol in the blood.
When added to a cell culture of HepG2 liver cells, lunasin slashed HMG-CoA reducstase expression by 50%. HMG-CoA is the gene that directs production of HMG-CoA reductase, the enzyme responsible for cholesterol biosynthesis. (Statin drugs also lower cholesterol by blocking HMG-CoA reductase.)
At the same time, lunasin increased by 60% the expression of the gene which produces LDL cholesterol receptors that help clear plasma cholesterol.