Effect of intestinal production of equol on menopausal symptoms in women treated with soy isoflavones

Int J Gynaecol Obstet. 2008 Jul;102(1):44-9. doi: 10.1016/j.ijgo.2008.01.028. Epub 2008 Apr 8.


Objective: To evaluate the effect of soy isoflavones on menopausal symptoms in women who do and who do not produce equol, a daidzein metabolite.

Method: A randomized, double-blind, placebo-controlled clinical trial was conducted over 6 months with 96 healthy menopausal women. After taking take 135 mg of isoflavones daily for 1 week, the women in the study group were assigned to the equol-producing (EP) or the non-EP group according to the presence or absence of equol in their urine. Menopausal symptoms were evaluated using a modified Kupperman Index.

Result: Compared with the placebo group, the scores for hot flashes and excessive sweating were significantly reduced after 3 months, and the scores for weakness, palpitations, limb paresthesia, and total symptoms after 6 months, in the EP group only.

Conclusions: Isoflavone supplementation improves menopausal symptoms only in women with the ability to produce equol.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Dietary Supplements*
  • Double-Blind Method
  • Equol
  • Female
  • Hot Flashes / prevention & control*
  • Humans
  • Intestinal Mucosa / metabolism
  • Isoflavones / biosynthesis
  • Isoflavones / therapeutic use*
  • Middle Aged
  • Phytoestrogens / therapeutic use*
  • Postmenopause / drug effects
  • Soybean Proteins / administration & dosage*


  • 4',7-dihydroxy-3,4-dihydroisoflavone
  • Isoflavones
  • Phytoestrogens
  • Soybean Proteins
  • Equol