Soy Protein Intake by Perimenopausal Women Does Not Affect Circulating Lipids and Lipoproteins or Coagulation and Fibrinolytic Factors

Abstract

Soy protein favorably alters serum lipids and lipoproteins in hypercholesterolemic individuals, thereby reducing cardiovascular disease risk. The primary purpose was to determine the effect of soy protein (40 g/d) on circulating lipids and lipoproteins or coagulation and fibrinolytic factors in normocholesterolemic and mildly hypercholesterolemic perimenopausal women. We also determined the contribution of coagulation and fibrinolytic and other factors (e.g., body size and composition; serum estrogens, ferritin, iron; dietary intake) to lipid profiles. Subjects were randomly assigned to treatment: isoflavone-rich soy (n = 24), isoflavone-poor soy (n = 24), or whey control (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 affected by treatment. Treatment did not alter lipid profiles in mildly hypercholesterolemic (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 to various factors, but at baseline accounted for 57% of the variability in HDL cholesterol (P < or = 0.0001) and for 50% in the total to HDL cholesterol ratio (P < or = 0.0001). Dietary vitamin E and % energy from fat had positive effects, whereas plasma plasminogen activator 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 fibrinolytic factors, whereas the effect of time suggested that the hormonal milieu during the menopausal transition may have overridden any detectable treatment effect on lipids. The relationship between coagulation factors and serum lipids should be examined further as indices of cardiovascular disease risk in midlife women.

Relation between soy-associated isoflavones and LDL and HDL cholesterol concentrations in humans: a meta-analysis

“…Nine of the 40 were included in the analysis (Baum et al, 1998;Crouse et al, 1999;Ashton & Ball, 2000;Teixeira et al, 2000;Vigna et al, 2000;Dent et al, 2001;Gardner et al, 2001;Teede et al, 2001;Van Horn et al, 2001). We also used data from one study in press at the time we submitted our manuscript (Jenkins et al, 2002).…”

“…Two trials were carried out in men only (Ashton & Ball, 2000;Teixeira et al, 2000), three studies included men and women (Crouse et al, 1999;Teede et al, 2001;Jenkins et al, 2002), and five studies included women only (Baum et al, 1998;Vigna et al, 2000;Dent et al, 2001;Gardner et al, 2001;Van Horn et al, 2001). The average age of the volunteers ranged from 41 to 63 y, mean body mass index ranged from 24 to 28 kg/m 2 , and mean baseline cholesterol concentration ranged from 5.42 to 6.60 mmol/l.…”

“…The change in isoflavones ranged from 1 to 95 mg/day as compared to the control group or treatment. Isoflavone dose is expressed in aglycone units in six studies (Baum et al, 1998;Crouse et al, 1999;Teixeira et al, 2000;Dent et al, 2001;Gardner et al, 2001;Jenkins et al, 2002). One study (Teede et al, 2001) reports 'basic compound plus respective glycosides', which we divided by 1.666 to convert them to aglycone units.…”

Dietary phytoestrogens and plasma lipids in Dutch postmenopausal women; a cross-sectional study

“…Furthermore, the meta-analysis combined studies in both males and females and did not discriminate between pre-and postmenopausal women. After publication of the meta-analysis several trials aiming specifically at postmenopausal women found, in contrast to the meta-analysis, no significant effect on cholesterol, LDL or HDL [18][19][20][21][22][23] except for two studies [24,25]. Effects of phytoestrogens might be different in preand postmenopausal women.…”

“…Data regarding Lp(a) and phytoestrogens is inconsistent, three trials reported an increase in Lp(a), one a decrease [18,22,25], while studies on HST show decreases of Lp(a) [29]. As far as we know we are the first to look at Lp(a) levels in relation to dietary phytoestrogens.…”