Isoflavones from red clover improve systemic arterial compliance but not plasma lipids in menopausal women

The possibility that the heightened cardiovascular risk associated with the menopause can be reduced by increasing dietary isoflavone intake was teste d in 17 women by measuring arterial compliance, an index of the elasticity of large arteries such as the thoracic aorta. Compliance diminishes with ag e and menopause. An initial 3- to 4-week run-in period and a 5-week placebo period were foll owed by two 6-week periods of active treatment with 40 mg and then 80 mg is oflavones derived from red clover containing genistein, daidzein, biochanin , and formononetin in 14 and 13 women, respectively, with 3 others serving as placebo controls throughout. Arterial compliance, measured by ultrasound as a pressure (carotid artery) and volume (outflow into aorta) relationshi p, was determined after each period; plasma lipids were measured twice duri ng each period. Urinary output of isoflavones was also determined. Arterial compliance rose by 23% relative to that during the placebo period with the 80-mg isoflavone dose and slightly less with the 40-mg dose (mean +/- SEM: placebo, 19.7 +/-: 1.5; 40 mg, 23.7 +/- 0.7; 80 mg, 24.4 +/- 1.4). In the three women receiving continuous placebo, compliance was 16 +/- 2.2 , similar to that during the run-in period for the remaining subjects (17 /- 2.1). ANOVA showed a significant (P = < 0.001) difference between treatm ents; by Bonferroni multiple comparisons and by paired t test, differences were significant between placebo and 40- and 80-mg isoflavone doses (by pai red t test: P = 0.039 for placebo vs. 40 mg; P = 0.018 for placebo us. 80 m g). Plasma lipids were not significantly affected. An important cardiovascular risk factor, arterial compliance, which diminis hes with menopause, was significantly improved with red clover isoflavones. As diminished compliance leads to systolic hypertension and may increase l eft ventricular work, the findings indicate a potential new therapeutic app roach for improved cardiovascular function after menopause.