Impact of soy supplementation on sex steroids and vascular inflammation markers in postmenopausal women using tibolone: role of equol production capability

Abstract

Objectives Tibolone is often taken concurrently with soy. Tibolone, soy and equol-producing capacity each affect vascular health, whereas their concomitant effects are unknown. We studied the effects of soy on sex steroids and vascular inflammation markers in long-term tibolone users.

Methods Postmenopausal women (n = 110) on tibolone were screened with a soy challenge to find 20 equol producers and 20 non-producers. All women were treated for 8 weeks in a cross-over trial with soy (52 g of soy protein containing 112 mg of isoflavones) or placebo. Serum estrone, 17β-estradiol, testosterone, androstenedione, dehydroepiandrosterone sulfate (DHEAS), sex hormone binding globulin (SHBG), C-reactive protein (CRP), vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), and platelet-selectin (P-selectin) were assessed.

Results Soy decreased (7.1%) the estrone level, significantly (12.5%) only in equol producers (from 80.2 ± 10.8 to 70.3 ± 7.0 pmol/l; p = 0.04). Testosterone was reduced (15.5%; from 586 ± 62.6 to 495 ± 50.1 pmol/l, p = 0.02) during soy treatment, and more markedly in equol producers than non-producers (22.1% vs. 10.0%). No changes appeared in SHBG, CRP or ICAM-1, but VCAM-1 increased (9.2%) and P-selectin decreased (10.3%) during soy treatment.

Conclusions Soy modified the concentrations of estrone, testosterone and some endothelial markers. Equol production enforced these effects. Soy supplementation may be clinically significant in tibolone users.

Key words:

• ISOFLAVONES
• ESTROGENS
• ANDROGENS
• CARDIOVASCULAR MARKERS
• HORMONE THERAPY