Original research
Benefits of soy isoflavone therapeutic regimen on menopausal symptoms

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Abstract

OBJECTIVE:

To examine the change in menopausal symptoms and cardiovascular risk factors in response to 4 months of daily 100-mg soy isoflavone in postmenopausal women.

METHODS:

In this double-blind, placebo-controlled study, 80 women were randomly assigned to isoflavone (n = 40) and placebo (n = 40) treatment. The menopausal Kupperman index was used to assess change in menopausal symptoms at baseline and after 4 months of treatment. Cardiovascular risk factors were assessed by evaluating plasma lipid levels, body mass index, blood pressure, and glucose levels in the participants. To examine the effects of this regime on endogenous hormone levels, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and 17β-estradiol were measured. Transvaginal sonography was performed to quantify endometrial thickness.

RESULTS:

The data showed a decrease in menopausal symptoms (P < .01, paired t test, two-tailed, between baseline and isoflavone groups, and P < .01, unpaired t test, between placebo and isoflavone groups). Total cholesterol and low-density lipoprotein decreased significantly in the isoflavone group compared with the baseline or placebo group (P < .001, paired t test, two-tailed, between baseline and isoflavone groups, and P < .01, unpaired t test, between placebo and isoflavone groups). The isoflavone treatment appeared to have no effect on blood pressure, plasma glucose, and high-density lipoprotein and triglyceride levels.

CONCLUSION:

This study suggests that isoflavone 100-mg regime treatment may be a safe and effective alternative therapy for menopausal symptoms and may offer a benefit to the cardiovascular system.

Section snippets

Materials and methods

This study was a randomized, double-blind, placebo-controlled trial designed to investigate the extent to which isoflavone 100 mg per day (Eugenbio Co. Ltda, Seoul, South Korea) decreased menopausal symptoms as well as affected cardiovascular risk and endogenous hormone levels. Subjects for the present study consisted of women aged 45–55 years who attended screening and baseline visits and were subsequently enrolled in the isoflavone program in the Division of Endocrinological Gynecology and

Results

The epidemiologic and clinical characteristics of age, race, education, and social status, use of nicotine and dietary and nutritional habits, and clinical problems were similar in both groups (Table 1). Subjects reported no consumption of alcohol. All participants exercised less than three times per week.

To evaluate the menopausal symptoms, the menopausal Kupperman index questionnaire was applied. In the first visit, symptoms were similar between placebo and isoflavone groups (Table 2).

Discussion

Some critics might question the optimal daily dose required to recognize a clinical response. Some authors cited a per capita estimated intake of 50–200 mg of iosflavone daily in an Asian diet.23, 24 Also, others may consider the length of time on the soy isoflavones as too short to elicit a clinical response.16 However, it has been determined that genistein and diadzein plasma concentrations peak 6–8 hours after ingestion.25 These data endorse our choice of 33.3 mg 8/8 hours per day as

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    We would like to thank Dr. Mercedes C. Panizzi; Marcos G. Mandarino and Dr. Akio Kikuchi (Brazilian Research Institute of Agriculture [EMBRAPA], Brasilia, Brazil); Dr. Tai W. Kwon and Dr. Sung R. Kim (Korea Food Research Institute, Seoul, Korea); Dr. Dong K. Yim (Food Technology of Campinas-[ITAL]), Campinas, Brazil; and Dr. Myoung K. Park (Life Science Research Center of Eugenbio Inc., Seoul, Korea) for their priceless efforts and cooperation in our study.

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