Equol production capability is associated with favorable vascular function in postmenopausal women using tibolone; no effect with soy supplementation.
OBJECTIVE
Equol, a gut bacterial metabolite of isoflavone daidzein, may improve health through changes in vascular function and in estrogen metabolism. Tibolone, a synthetic steroid alternative for the treatment of postmenopausal symptoms, causes a different estrogenic milieu than estrogen and may affect vascular health. We studied the effects of equol production and soy supplementation on vascular function in postmenopausal women under long-term tibolone use.


METHODS
We screened 110 women using tibolone for 3-60 months for high equol production capacity with a one-week soy challenge. Twenty women with high equol production capacity (4-fold elevation in equol level) and 20 comparable control women without this capacity were treated in a randomized placebo-controlled cross-over trial with a soy drink (52 g of soy protein containing 112 mg of isoflavones) or placebo for 8 weeks. Arterial stiffness and endothelial function were assessed before and after soy and placebo supplementation with pulse-wave analysis.


RESULTS
Prior to soy supplementation arterial stiffness, expressed as augmentation index, was lower (p=0.01) in equol producers (25.9+/-1.1%) than non-equol producers (29.6+/-0.9%). Similarly, endothelial function index was better at baseline (p=0.009) in these women (72.3+/-5.3%) compared to women lacking equol production capacity (55.2+/-3.8%). Soy supplementation had no effect on arterial stiffness or endothelial function in either group.


CONCLUSIONS
In postmenopausal tibolone users, endogenous equol production capability is associated with favorable vascular function. This phenomenon was not affected by soy and thus, equol producing capacity may be an independent vascular health marker, at least in postmenopausal women using tibolone.
Törmälä
Riina
R
Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Finland.
Appt
Susan
S
Clarkson
Thomas B
TB
Groop
Per-Henrik
PH
Rönnback
Mats
M
Ylikorkala
Olavi
O
Mikkola
Tomi S
TS
D000368:Aged; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism; D002318:Cardiovascular Diseases / Q000503:physiopathology / Q000517:prevention & control*; D003187:Compliance / Q000187:drug effects; D004359:Drug Therapy, Combination; D060754:Equol; D020847:Estrogen Receptor Modulators / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007422:Intestines / Q000382:microbiology; D007529:Isoflavones / Q000096:biosynthesis*; D008875:Middle Aged; D009652:Norpregnenes / Q000008:administration & dosage*; D048789:Phytoestrogens / Q000378:metabolism*; D017698:Postmenopause / Q000187:drug effects; D011673:Pulsatile Flow / Q000187:drug effects; D030262:Soybean Proteins / Q000008:administration & dosage*
C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D020847:Estrogen Receptor Modulators; D007529:Isoflavones; D009652:Norpregnenes; D048789:Phytoestrogens; D030262:Soybean Proteins; D060754:Equol; C027385:tibolone