Serum cholesterol efflux potential in postmenopausal women treated with isolated isoflavones.
OBJECTIVE
Based on the low cardiovascular risk in Asian populations, phytoestrogens are believed to provide vascular benefits. To elucidate the mechanisms behind the possible cardiovascular effects of phytoestrogens, we evaluated reverse cholesterol transport by assessing the capacity of serum to promote cholesterol efflux in postmenopausal women treated with isolated isoflavones.


METHODS
Thirty postmenopausal women were treated in a randomized, placebo-controlled, crossover trial with isoflavones or placebo for 3 months interrupted by a 2-month washout period. Serum samples were collected before and after each treatment period, and the cholesterol efflux potential was investigated by using H-cholesterol--labeled Fu5AH cells in culture.


RESULTS
Serum promoted 20.2% +/- 3.0% and 19.9% +/- 3.4% (mean +/- SD) cholesterol efflux after isoflavonoid treatment and after placebo treatment, respectively. Thus, the isoflavone treatment did not affect serum cholesterol efflux. We also studied separately women who produced high concentrations of the isoflavone metabolite equol into serum because some studies suggest that equol could exert favorable vascular effects. However, there was no difference in serum cholesterol efflux capacity between the equol producers (n = 15) and non-equol producers (n = 15).


CONCLUSIONS
In conclusion, isoflavone treatment did not affect serum cholesterol efflux potential in postmenopausal women. Based on our findings, isolated isoflavones do not provide vascular benefits by improving cholesterol efflux.
Törmälä
Riina M
RM
Department of Obstetrics and Gynecology, Helsinki University Central Hospital, Finland.
Nikander
Eini
E
Tiitinen
Aila
A
Väisänen-Tommiska
Mervi
M
Ylikorkala
Olavi
O
Mikkola
Tomi S
TS
D000328:Adult; D000368:Aged; D002460:Cell Line; D002784:Cholesterol / Q000097:blood*; D004311:Double-Blind Method; D060754:Equol; D005260:Female; D019833:Genistein / Q000097:blood; D006801:Humans; D007529:Isoflavones / Q000097:blood / Q000627:therapeutic use*; D008055:Lipids / Q000097:blood; D008074:Lipoproteins / Q000097:blood; D008875:Middle Aged; D010919:Placebos; D017698:Postmenopause / Q000097:blood*; D014316:Tritium
C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D007529:Isoflavones; D008055:Lipids; D008074:Lipoproteins; D010919:Placebos; D014316:Tritium; D060754:Equol; C004742:daidzein; D002784:Cholesterol; D019833:Genistein