Soy protein intake by perimenopausal women does not affect circulating lipids and lipoproteins or coagulation and fibrinolytic factors

Soy protein favorably alters serum lipids and lipoproteins in hypercholeste rolemic individuals, thereby reducing cardiovascular disease risk. The prim ary purpose was to determine the effect of soy protein (40 g/d) on circulat ing lipids and lipoproteins or coagulation and fibrinolytic factors in norm ocholesterolemic and mildly hypercholesterolemic perimenopausal women. We a lso determined the contribution of coagulation and fibrinolytic and other f actors (e.g., body size and composition; serum estrogens, ferritin, iron; d ietary intake) to lipid profiles. Subjects were randomly assigned to treatm ent: isoflavone-rich soy (n = 24), isoflavone-poor soy (n = 24), or whey co ntrol (n = 21) protein. We measured circulating lipids and lipoproteins at baseline, wk 12 and wk 24, and coagulation/fibrinolytic factors at baseline and wk 24. Coagulation and fibrinolytic factors were not adversely affecte d by treatment. Treatment did not alter lipid profiles in mildly hyperchole sterolemic (n = 30) or in all subjects combined. Time significantly (P < 0. 001) affected serum total cholesterol, triacylglycerol, LDL cholesterol and HDL cholesterol concentrations. We could not attribute changes over time t o various factors, but at baseline accounted for 57% of the variability in HDL cholesterol (P less than or equal to 0.0001) and for 50% in the total t o HDL cholesterol ratio (P less than or equal to 0.0001). Dietary vitamin E and % energy from fat had positive effects, whereas plasma plasminogen act ivator inhibitor-1, fibrinogen, body weight and serum ferritin had negative effects on HDL and total to HDL cholesterol. Isoflavone-rich or isoflavone -poor soy protein had no effect on lipid profiles or coagulation and fibrin olytic factors, whereas the effect of time suggested that the hormonal mili eu during the menopausal transition may have overridden any detectable trea tment effect on lipids. The relationship between coagulation factors and se rum lipids should be examined further as indices of cardiovascular disease risk in midlife women.