Effects of isoflavones and amino acid therapies for hot flashes and co-occurring symptoms during the menopausal transition and early postmenopause: a systematic review

Maturitas. 2014 Aug;78(4):263-76. doi: 10.1016/j.maturitas.2014.05.007. Epub 2014 May 28.


Aims: Review controlled clinical trials of isoflavones and amino acid preparation effects on hot flashes and at least one other symptom including mood, sleep, pain, and cognitive function that women report during the menopausal transition and early postmenopause.

Methods: An experienced reference librarian searched PubMed/Medline, CINAHL Plus, PsycInfo, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, Web of Science, EMBASE, AMED, and Alt-Health Watch for English-language randomized controlled trials between 2004 and July 2011. Seventeen trials of isoflavones and amino acid effects on hot flashes and one additional symptom were identified.

Results: In five trials of soy isoflavone preparations, two (6g soy germ extract and 25 g soy protein in soy nuts) significantly decreased hot flashes, but no other symptoms. In the seven trials of other isoflavones, six significantly reduced hot flashes; in addition, red clover (80 mg) significantly reduced mood symptoms; Rexflavone (350 mg) for women with Kupperman Index>20 significantly reduced sleep symptoms; two trials had significant reductions for pain: isoflavone powder (90 mg) and red clover (80 mg). The only trial in this systematic review that significantly reduced cognitive symptoms was red clover (80 mg). In one trial, red clover isoflavone (80 mg/day) significantly relieved hot flashes, mood, pain, and cognitive symptoms. Amino acids yielded no significant results. Equol supplements of 30 mg/day for non-Equol producing women significantly reduced mood symptoms in one trial. The magnolia bark extract combination significantly reduced hot flashes, mood, and sleep symptoms.

Conclusions: Isoflavone trials yielded significant reductions on hot flashes and co-occurring symptoms during the menopausal transition and postmenopause, but studies require replication with larger sample sizes and attention to measurement of outcomes.

Keywords: Amino acids; Hot flashes; Isoflavones; Menopausal transition; Soy; Symptom clusters.

Publication types

  • Research Support, N.I.H., Extramural
  • Review
  • Systematic Review

MeSH terms

  • Affect / drug effects*
  • Amino Acids / pharmacology*
  • Cognition Disorders / complications
  • Cognition Disorders / drug therapy*
  • Female
  • Hot Flashes / complications
  • Hot Flashes / drug therapy*
  • Humans
  • Isoflavones / pharmacology
  • Isoflavones / therapeutic use*
  • Menopause
  • Pain / complications
  • Pain / drug therapy*
  • Phytoestrogens / pharmacology
  • Phytoestrogens / therapeutic use
  • Postmenopause
  • Sleep Wake Disorders / complications
  • Sleep Wake Disorders / drug therapy*


  • Amino Acids
  • Isoflavones
  • Phytoestrogens