Effects of red clover (Trifolium pratense) isoflavones on menopausal metabolic syndrome : Systematic review

It is of great importance to manage and prevent metabolic syndrome in menopausal women because metabolic syndrome can increase the mortality rate of cardiovascular disease, cerebrovascular disease, and type 2 diabetes. Although estrogen replacement therapy can improve components of metabolic syndrome and reduce the incidence of cardiovascular disease and type 2 diabetes, alternatives are needed due to harmful effects such as cancer of the reproductive system. Therefore, the present systematic review aimed to examine effects of red clover (Trifolium pratense) supplementation on menopausal metabolic syndrome by extensively investigating randomized controlled trials (RCTs). We performed literature search that was limited to papers written in English using keywords ‘menopause’, ‘metabolic syndrome’, and ‘red clover’ in PubMed and Embase. As a result, 20 papers were included in the systematic review. Most isoflavones derived from red clover were supplied in tablet or capsule form with a dosage of 37 to 160 mg/day. The period of supplementation with isoflavones ranged from 4 weeks to 2 years. The average of age of study subjects was 47 to 68 years. Most RCTs measured blood lipids and half of included studies showed significant effects of red clover supplementation on one or more measured indicators. Most studies investigating weight, body mass index, body fat, blood pressure, and glucose metabolism-related indicators did not show significant effects. The quality of included studies was evaluated as high except for one study by Jadad scale. Large-scale clinical research is needed to determine the effectiveness of plant-derived functional materials in improving menopausal metabolic syndrome.