Effect of soy nuts and equol status on blood pressure, lipids and inflammation in postmenopausal women stratified by metabolic syndrome status

Abstract

Objective: Soy has been associated with lower risk of cardiovascular disease in Asian countries which consume daily soy. Our study examined whether production of equol, an estrogen metabolite, affected the ability of soy nuts to improve cardiovascular risk factors.

Materials/methods: Sixty postmenopausal women participated in a randomized, controlled, crossover trial of a Therapeutic Lifestyle Changes (TLC) diet alone and a TLC diet in which 0.5 cup of soy nuts (25 g of soy protein and 101 mg of aglycone isoflavones) replaced 25 g of nonsoy protein daily. Each diet was followed for 8 weeks at the end of which blood pressure (BP), lipid levels, adhesion molecules and inflammatory markers were measured.

Results: Women with MetS had significantly higher baseline body mass index (BMI), BP, triglycerides (TG), and soluble intercellular adhesion molecule (sICAM) than women without MetS. In women with MetS on the soy diet, significant reductions in diastolic BP (7.7%; P=0.02), TG (22.9%; P=0.02), C-reactive protein (CRP) (21.4%; P=0.01) and sICAM (7.3%; P=0.03) were noted among equol producers compared to levels on the TLC diet. No significant changes were noted in equol nonproducers. Similarly, in women without MetS, only equol producers had significant reductions in diastolic BP (3.3%, P=0.02) and CRP (30%, P=0.04). In contrast to women with MetS, TG and sICAM levels were not affected in women without MetS, a finding possibly related to lower baseline levels.

Conclusions: Cardiovascular risk reduction with soy nuts is not uniform and may be greater among producers of equol.

Trial registration: ClinicalTrials.gov NCT01740076.

Keywords: Blood pressure; Equol; Isoflavones; Metabolic syndrome; Soy protein.

Figure 1

Percent change on soy diet compared to control diet in women with metabolic syndrome among equol producers (dark bars) and equol nonproducers (lighter bars). P values are for soy vs control diet.

Figure 2

Percent change on soy diet compared to control diet in women without metabolic syndrome among equol producers (dark bars) and equol nonproducers (lighter bars). P values are for soy vs control diet.