Cholesterol-lowering effect of soy protein in normocholesterolemic and hypercholesterolemic men

Cardiovascular heart disease is a major health problem in the United States . Elevated blood cholesterol has been shown to significantly increase the r isk of cardiovascular heart disease. The National Cholesterol Educational P rogram (NCEP) Step I diet, which restricts fat and cholesterol intakes, is usually recommended as the initial treatment to lower blood cholesterol. So y protein has been shown to be hypocholesterolemic, particularly in hyperch olesterolemic subjects. However, the hypocholesterolemic effect of soy prot ein in subjects with a blood total cholesterol concentration <5.17 mmol/L i s not clear. To determine whether soy protein could enhance the hypocholest erolemic effect of the NCEP Step I diet, 13 normocholesterolemic and 13 hyp ercholesterolemic men aged 20-50 y were enrolled in a randomized, 2-part, c rossover study. Subjects were fed either an NCEP Step I soy-protein diet or an NCEP Step I animal protein diet for 5 wk. After a washout period of 10- 15 wk, the subjects were fed the alternate diet for 5 wk. The hypocholester olemic effect of soy protein was found to be independent of age, body weigh t, pretreatment plasma lipid concentrations, and sequence of dietary treatm ent. Regardless of plasma lipid status, the soy-protein diet was associated with a statistically significant decrease in the plasma concentrations of LDL cholesterol (P = 0.029) as well as the in the ratio of plasma LDL chole sterol to HDL cholesterol (P = 0.005). Our results indicate that soy protei n enhances the hypocholesterolemic effect of the NCEP Step I diet in both n ormocholesterolemic and hypercholesterolemic men.