JAMA

JAMA: Isoflavones Questionable for Hot Flashes

PORTLAND, Ore.Supplementationwith isoflavones may not benefit menopausal women suffering from hot flashes,according to a review and meta-analysis comparing the natural therapy alongsideseveral drugs (JAMA, 295, 17:2057-71, 2006) (http://jama.ama-assn.org/).

Researchers from Oregon Health and Science University, Veterans AffairsMedical Center and Women and Providence Health System combed MEDLINE(1966-October 2005), PsycINFO (1974- October 2005), and the Cochrane ControlledClinical Trials Register Database (1966-October 2005) for relevant,English-language, published, randomized, double blind, placebo-controlled trialsproviding data on treatment of hot flashes in menopausal women measuring andreporting hot flash frequency or severity outcomes and using one or more oral,nonhormonal therapies. Of 4,249 abstracts found, the researchers selected 43relevant studies, including 10 trials of antidepressants, 10 trials ofclonidine, six trials of other prescribed medications and 17 trials ofisoflavone extracts.The number of daily hot flashes decreased compared withplacebo in meta-analyses of seven comparisons of selective serotonin reuptakeinhibitors (SSRIs) or serotonin norepinephrine reuptake inhibitors (SNRIs), fourtrials of the antihypertensive agent clonidine, and two trials of gabapentin, adrug commonly prescribed to control epileptic seizures. Frequency of hot flasheswas not reduced in meta-analysis of trials of red clover isoflavone extracts andresults were mixed for soy isoflavone extracts.The researchers noted therelative efficacy of the treatments cannot be determined, as the trials theyreviewed do not compare different therapies head-to-head. The researchersconcluded SSRIs or SNRIs, clonidine, and gabapentin trials provide evidence forefficacy; however, effects are less than for estrogen, few trials have beenpublished and most have methodological deficiencies, generalizability islimited, and adverse effects and cost may restrict use for many women, and notedthese therapies may be most useful for highly symptomatic women who cannot takeestrogen but are not optimal choices for most women.

Since anti-depressants appear to offer some efficacy for hot flashes,black cohosh, which has been shown to act on a serotonin receptor subtype, mayproduce anti-depressant effects and also provide a safe and efficacioustreatment, said Steven Dentali, Ph.D., vice president for scientific andtechnical affairs for the American Herbal Products Association (AHPA). Further,we know that black cohosh does not appear to work through an estrogenic pathwaylike soy isoflavones do, which should alleviate any concern that black cohoshcould produce the same side effects associated with hormone therapy.