Rapid Publication Soybean Protein Diet Increases Low Density Lipoprotein Receptor Activity in Mononuclear Cells from Hypercholesterolemic Patients

The effect of two diets containing different protein sources (animal vs. soybean) on the low density lipoprotein (LDL) re-ceptor activity was tested in freshly isolated mononuclear cells from 12 individuals with severe type II hyperlipoproteinemia. The two diets, both taken for 4 wk in a crossover design were of otherwise identical composition. During the soybean protein diet period, total cholesterol was reduced by 15.9 % and LDL-cholesterol by 16.4%. The diet containing animal proteins ex-erted no significant change in plasma lipid levels vs. the base-line findings. The soybean diet regimen dramatically affected the degradation of LDL by mononuclear cells. Degradation was increased 16-fold vs. the basal activity and 8-fold com-pared with the standard low lipid diet with animal proteins. There was, however, no clear relationship between the reduc-tion of total and LDL-cholesterolemia and the increased LDL degradation. These findings confirm similar data previously obtained in cholesterol-fed rats and suggest that some factor/s, most likely of a protein nature, may regulate the expression of lipoprotein receptors in peripheral cells, particularly when re-ceptor activity is suppressed by experimental diets and/or spontaneous hypercholesterolemia