This randomized, double-blind, placebo-controlled clinical trial with 96 menopausal women was conducted over 6 months. 66 women were given 135 mg of soy isoflavone and 30 women were given placebo. After one week, the women in the treatment group were tested and further divided into 2 subgroups, equol-producing (EP) and non equol-producing (non-EP), according to peak levels of equol in the urine. Women in both of these subgroups were then given 3 grams of soy germ extract powder twice a day, totaling 135 mg of isoflavones daily, for 6 months.Menopause symptoms were evaluated using a modified Kupperman Index, measuring 17 items (hot flashes, excessive sweating, coldness of extremities, shortness of breath, numbness of extremities, paresthesia of extremities, insomnia, easy awakening, excitability, nervousness, melancholia, vertigo, weakness, arthralgia or myalgia, headaches, palpitations and formication. and scoring them as none, mild, moderate or severe.
Compared with the placebo group, symptoms of hot flashes and excessive sweating significantly reduced after 3 months and weakness, palpitations, limb paresthesias and total symptoms significantly decreased after 6 months, (P< 0.05) but only in the equol producers. At 3 months, total scores had decreased by 66% in the EP group, 54% in the non-EP group and 59% in the placebo group. At 6 months, symptom scores had decreased by 84% in the EP group, 58%in the non-EP group and 66 % for the placebo group.
Jou H-J, Wu S-S, Change F-W, Ling P-Y, Chue K, Wu W-H. Effect of intestinal production of equol on menopausal symptoms in women treated with soy isoflavones. Intl J Gynecology and Obstetrics (2008), doi: 10.1016/j.ijgo. 2008.01.028
Commentary: The research on soyâ€™s ability to relieve menopause symptoms has produced quite mixed results. Differences in study doses, different proportions of genistein and daidzein used in the study medication, and differences in the study population have been used to explain the discrepancies. Study populations who may have a higher percentage of women who are equol producers have been previously suspected to be the determining factor in the effectiveness of soy isoflvaones, but the current study seems to be the first to demonstrate more clearly that a womanâ€™s ability to produce equol determines her response to soy isoflavone supplementation. Daidzein and genestien are the two most significant phytoestrogens in soy. Daidzein is converted to equol, a metabolite of daidzein, by bacterial flora in the gut. It may be appropriate to test for equol production prior to treatment of perimenopausal and menopausal women to achieve the most success, and/or improve gut flora so that the individuals can more easily transform soy isoflavones to equol. This can be done with improving oneâ€™s diet to whole foods nutrition, reducing sugar to a minimum, consuming mostly unsaturated fats, and possibly taking probiotics as a nutritional supplement or in quality yogurts.