Effect of soy isoflavones on circulating C-reactive protein ... : Menopause (original) (raw)

Review Article

Effect of soy isoflavones on circulating C-reactive protein in postmenopausal women

meta-analysis of randomized controlled trials

Dong, Jia-Yi BSc1; Wang, Peiyu MD, PhD2; He, Ka MD, ScD3; Qin, Li-Qiang MD, PhD1

From the 1Department of Nutrition and Food Hygiene, School of Radiation Medicine and Public Health, Soochow University, Suzhou, China; 2Department of Social Medicine and Health Education, School of Public Health, Peking University, Beijing, China; and 3Department of Nutrition, Gillings School of Global Public Health and School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC.

Received February 26, 2011; revised and accepted March 23, 2011.

Financial disclosure/conflicts of interest: None reported.

Address correspondence to: Li-Qiang Qin, MD, PhD, Department of Nutrition and Food Hygiene, School of Radiation Medicine and Public Health, Soochow University, 199 Renai Road, Dushu Lake Higher Education Town, Suzhou, 215123 China. E-mail: [email protected]

Abstract

Strong evidence suggests that C-reactive protein (CRP) is a novel risk factor for cardiovascular disease. We aimed to examine the effect of soy isoflavones on circulating CRP concentrations in postmenopausal women by conducting a meta-analysis of randomized controlled trials. We performed a literature search using PubMed, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov databases in December 2010 for randomized controlled trials conducted in postmenopausal women, using soy foods with isoflavones or isoflavone extracts as treatment, and with a report of CRP change. A meta-analysis was performed using a fixed-effects model or a random-effects model to calculate the combined effect size. In addition, subgroup and metaregression analyses were carried out to examine the influences of study designs and participant characteristics on the effect estimates. A pooled analysis of 14 trials showed a slight, but not significant, reduction of 0.17 mg/L (95% CI, −0.38 to 0.04; P = 0.12) in CRP concentrations among postmenopausal women with soy isoflavone intervention compared with controls. No substantial heterogeneity was observed. Subgroup analyses showed that soy isoflavones significantly lowered CRP by 0.70 mg/L (95% CI, −1.17 to −0.23; P = 0.003) among women with baseline CRP concentrations greater than 2.2 mg/L. No significant changes in CRP were observed in the other subgroups. Metaregression analysis further revealed that baseline CRP was a potential effect modifier of isoflavone treatment in lowering CRP. The present meta-analysis found insufficient evidence that soy isoflavones significantly reduce CRP concentrations in postmenopausal women. However, soy isoflavones may produce a significant reduction in CRP among postmenopausal women with elevated CRP.