Meta-analysis Of The Safety Of Soybean Isoflavones In Postmenopausal Women

Backgrounds Menopause is a natural physiological stage during women's life Due to decreased endogenous estrogen level,women may suffer from a series of clinical manifestations named menopausal syndrome.Soybean isoflavones are natural phytoestrogens that can bind with estrogen receptors and play a weak estrogen-like role.When the in-vivo estrogen level is high,isoflavones also play an anti-estrogen role.The bidirectional regulation of soybean isoflavones might be beneficial for postmenopausal women.After menopause,the endogenous estrogen level in women is low,the weak estrogen-like effect of isoflavones might be helpful to avoid serious side effects of estrogen and selective estrogen receptor modulators when used in hormone replacement therapy.Previous systematic evaluations of soybean isoflavones for postmenopausal women mostly focused on the advantages such as preventing osteoporosis and regulating blood lipid levels.Recently,some clinical trials had reported that isoflavones also have some side effects when used in postmenopausal women.However,meta-analysis focused on the safety of isoflavones has not been high-lighted until nowObjective To evaluate the safety of soybean isoflavones for postmenopausal women by meta-analysis in order to provide evidence-based medical support for clinical use of isoflavonesMethods The academic databases of Pubmed,Science Direct and Google were searched in order to collect the literatures about soybean isoflavones used in postmenopausal women.Non-conforming literatures were excluded according to the formulated inclusive criteria.The quality of the included literatures were assessed using the Cochrane risk bias assessment tool recommended by the Cochrane Manual.RevMan 5.3 statistical software was used to synthesize and test the heterogeneity of the included literature data.Subgroup analysis was done according to the dose and the time of soybean isoflavone intake.Stata 13.0 software was used to test publication bias by Egger and Begg methods respectively.Sensitivity analysis was performed by removal of single-study method.GRADE system was used to evaluate the quality of the results.Results 34 articles were included.There were 2133 cases in the isoflavons group and 1740 cases in the control group.The number of adverse reactions is 1090 in the soybean isoflavone group and 1017 in the control group.No significant difference was found between the two groups in the number of total adverse reactions,as well as postmenopausal hemorrhage,breast tenderness,nervous system symptoms and cardiac discomfort(P>0.05).Only the number of gastrointestinal reactions was significantly higher in the isoflavones group than the control group(P<0.01).The subgroup analysis showed that the number of gastrointestinal reactions was higher in the isoflavones group only when the intake time was more than 6 months and the daily dose exceeded 80 mg as compared to the control group(P<0.00001).Conclusions Soybean isoflavones are safe for postmenopausal women.The using of isoflavones dose not increase the adverse reactions such as postmenopausal hemorrhage,breast tenderness,nervous system symptoms and cardiac discomfort.Gastrointestinal reactions increased only when the intake time of isoflavones is more than 6 months and the dose exceeds 80 mg per day.