Natural S-equol decreases bone resorption in postmenopausal, non-equol-producing Japanese women: a pilot randomized, placebo-controlled trial.
OBJECTIVE
Equol is a metabolite of the isoflavone daidzein and may play a critical role in preventing bone loss by soy isoflavones in postmenopausal women. However, results from clinical trials have not been published. The aim of this study was to investigate the effects of equol on bone metabolism and serum sex and thyroid hormone levels in postmenopausal Japanese women.


METHODS
We performed a 1-year double-blind, randomized, placebo-controlled trial with natural S-equol supplements for 93 non-equol-producing menopausal Japanese women. Participants were randomly assigned to four groups receiving the following: placebo, 2 mg of equol supplement per day, 6 mg of equol supplement per day, and 10 mg of equol supplement per day.


RESULTS
Equol intervention increased equol concentrations in serum and urine in a dose-dependent manner. Urinary deoxypyridinoline was significantly decreased, with a -23.94% change in the group that received 10 mg of equol supplement per day as compared with a -2.87% change in the group that received placebo after 12 months of intervention (P = 0.020). Thus, 10 mg/day of equol supplement markedly inhibited bone resorption. Treatment with 10 mg/day of equol prevented a decrease in bone mineral density in the entire body in postmenopausal women after 12 months. Sex and thyroid hormone concentrations in serum did not differ among the four groups after intervention.


CONCLUSIONS
These findings suggest that 10 mg/day of natural S-equol supplementation contributes to bone health in non-equol-producing postmenopausal women without adverse effects.
Food Function and Labeling Program, National Institute of Health and Nutrition, Tokyo, Japan.
Yuko
Y
Tousen
Junko
J
Ezaki
Yasuhiro
Y
Fujii
Tomomi
T
Ueno
Mamoru
M
Nishimuta
Yoshiko
Y
Ishimi
D000328:Adult; D000596:Amino Acids / Q000652:urine; D044466:Asian People; D015519:Bone Density / Q000187:drug effects*; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D001862:Bone Resorption / Q000188:drug therapy*; D019587:Dietary Supplements; D060754:Equol; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood; D006801:Humans; D007529:Isoflavones / Q000097:blood / Q000627:therapeutic use* / Q000652:urine; D008875:Middle Aged; D048789:Phytoestrogens / Q000097:blood / Q000627:therapeutic use* / Q000652:urine; D010865:Pilot Projects; D010919:Placebos; D017698:Postmenopause / Q000378:metabolism*; D013963:Thyroid Hormones / Q000097:blood
C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D000596:Amino Acids; D050071:Bone Density Conservation Agents; D012739:Gonadal Steroid Hormones; D007529:Isoflavones; D048789:Phytoestrogens; D010919:Placebos; D013963:Thyroid Hormones; D060754:Equol; C036020:deoxypyridinoline