A pilot study on the effects of S-equol compared to soy isoflavones on menopausal hot flash frequency

J Womens Health (Larchmt). 2012 Jun;21(6):674-82. doi: 10.1089/jwh.2011.3153. Epub 2012 Mar 12.


Background: S-equol, a metabolite of the soy isoflavone daidzein, has been proposed as having potential for relief of menopausal symptoms. This study compared the efficacy of the natural S-equol supplement, SE5-OH, with isoflavones for relieving hot flashes and other menopausal symptoms.

Methods: An 8-week randomized, double-blind, active comparator trial with SE5-OH was conducted in postmenopausal women (aged 45-65 years), who experienced ≥5 hot flashes/day. Participants (n=102) were assigned to one of four treatment groups: 10 (n=24), 20 (n=27), or 40 (n=25) mg S-equol/day or soy isoflavones (n=26). Participants recorded their hot flash frequency and rated their menopause symptom severity.

Results: Reductions in hot flash frequency at week 8 were similar for all treatment groups. However, based on analyses of the cumulative effect for the 8-week period, 40 mg/day S-equol had a greater reduction of hot flash frequency compared to isoflavones (p=0.021). A subgroup analysis further indicated that for subjects with >8 hot flashes/day at baseline, 20 and 40 mg/day S-equol were superior to isoflavones in reducing hot flash frequency (p=0.045 and p=0.001, respectively). In addition, 10 and 20 mg/day S-equol improved muscle and joint pain score compared with isoflavones (p=0.003 and p=0.005, respectively).

Conclusions: S-equol, 10 mg/day, appears to be as effective as soy isoflavones at reducing hot flash frequency and more effective for relieving muscle and joint pain in postmenopausal women. S-equol, ≥20 mg/day, alleviates hot flashes to a greater extent than soy isoflavones in those women who experience >8 hot flashes/day.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Dietary Supplements
  • Double-Blind Method
  • Female
  • Hot Flashes / drug therapy*
  • Hot Flashes / ethnology
  • Hot Flashes / metabolism
  • Humans
  • Isoflavones / blood
  • Isoflavones / therapeutic use*
  • Middle Aged
  • Osteoporosis, Postmenopausal / drug therapy
  • Osteoporosis, Postmenopausal / prevention & control
  • Phytoestrogens / blood
  • Phytoestrogens / therapeutic use*
  • Phytotherapy
  • Postmenopause / drug effects*
  • Postmenopause / metabolism
  • Soybean Proteins / blood
  • Soybean Proteins / therapeutic use*
  • Treatment Outcome
  • United States


  • Isoflavones
  • Phytoestrogens
  • SE5-OH
  • Soybean Proteins