Marked individual variation in isoflavone metabolism after a soy challenge can modulate the skeletal effect of isoflavones in premenopausal women.
Soy-isoflavones may act as estrogenic agonists or antagonists depending on the endogenous hormone status. These clinical effects can be exerted variably in individuals by the metabolic ability to produce a more potent metabolite than precursors. The objective of this randomized, double-blind, placebo-controlled study was to investigate the skeletal effect of isoflavones according to their metabolic variability in premenopausal women. Volunteers were randomly assigned to receive either soy-extract isoflavones (n=32) or lactose (n=21) once a day for three menstrual cycles. After intervention, the urinary excretions of isoflavones and their metabolites were significantly higher in the soy group than in the placebo group and showed a large inter-individual variation. Women in the soy group were divided into subgroups according to their ability to excrete more potent metabolites. Serum osteocalcin and urine deoxypyridinoline showed a tendency to increase after a challenge in equol high-excretors. Serum osteocalcin concentration in the genistein high-excretors increased significantly after a challenge (P=0.04) but did not increase in either the placebo or genistein low-excretors. An estrogenic antagonistic effect of isoflavones on bone turnover was observed in premenopausal women who are able to produce more potent metabolites.
Division of Endocrinology, Department of Internal Medicine, Cheil General Hospital and Women's Healthcare Center, Kwandong University School of Medicine, Seoul, Korea.
Ho Seok
HS
Kwak
So Young
SY
Park
Mi Gyeong
MG
Kim
Chang Hoon
CH
Yim
Hyun Koo
HK
Yoon
Ki Ok
KO
Han
D000328:Adult; D000596:Amino Acids / Q000652:urine; D001842:Bone and Bones / Q000187:drug effects* / Q000378:metabolism; D004311:Double-Blind Method; D004965:Estrogen Antagonists / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000652:urine; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood; D017697:Premenopause
D000596:Amino Acids; D004965:Estrogen Antagonists; D007529:Isoflavones; D015675:Osteocalcin; C036020:deoxypyridinoline