Individual differences in equol production capability modulate blood pressure in tibolone-treated postmenopausal women: lack of effect of soy supplementation.
OBJECTIVE
Equol, a gut bacterial metabolite of the isoflavone daidzein, has been associated with beneficial health effects. Recent studies indicate that women with intestinal capacity to convert daidzein to equol also have the capacity to alter steroid metabolism and bioavailability of estrogens.


METHODS
We evaluated whether individual equol production capability, while not consuming soy supplement, was associated with lower blood pressure in postmenopausal women using tibolone. In addition, in a randomized, placebo-controlled, cross-over trial we assessed the effect of soy supplementation on blood pressure in both equol-producing (n = 20) and non-equol-producing (n = 20) women using tibolone. Blood pressure was recorded with a validated oscillometric technique.


RESULTS
The circulating equol levels rose 20-fold in the equol producers and 1.9-fold in the non-equol producers. At baseline, systolic blood pressure (129.9 +/- 2.6 vs. 138.5 +/- 3.1 mmHg, p = 0.02), diastolic blood pressure (72.2 +/- 1.5 vs. 76.6 +/- 1.3 mmHg, p = 0.01) and mean arterial blood pressure (93.5 +/- 1.7 vs. 99.9 +/- 1.8 mmHg, p = 0.007) were lower in equol producers compared to non-equol producers. Soy supplementation had no effect on blood pressure in either group, whereas the baseline differences persisted.


CONCLUSIONS
Postmenopausal women using tibolone characterized as equol producers had lower blood pressure compared to non-equol producers. Soy supplementation for 2 months had no blood pressure-lowering effect.
Wake Forest University School of Medicine, Comparative Medicine Clinical Research Center, Winston-Salem, NC, USA.
R M
RM
Törmälä
S
S
Appt
T B
TB
Clarkson
M J
MJ
Tikkanen
O
O
Ylikorkala
T S
TS
Mikkola
D001794:Blood Pressure / Q000187:drug effects*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D060754:Equol; D020847:Estrogen Receptor Modulators / Q000008:administration & dosage*; D005260:Female; D019833:Genistein / Q000378:metabolism; D006801:Humans; D007529:Isoflavones / Q000096:biosynthesis*; D008297:Male; D008875:Middle Aged; D009652:Norpregnenes / Q000008:administration & dosage*; D048789:Phytoestrogens / Q000378:metabolism; D017698:Postmenopause / Q000097:blood* / Q000187:drug effects; D030262:Soybean Proteins / Q000008:administration & dosage*; D016896:Treatment Outcome; D016387:Women's Health
C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D020847:Estrogen Receptor Modulators; D007529:Isoflavones; D009652:Norpregnenes; D048789:Phytoestrogens; D030262:Soybean Proteins; D060754:Equol; D019833:Genistein; C027385:tibolone