Review| Volume 55, ISSUE 3, P203-211, October 20, 2006

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Isoflavone therapy for menopausal flushes: A systematic review and meta-analysis

  • Author Footnotes
    1 Previously performed contractual work and been a consultant for Novogen Pty Ltd, a manufacturer of Red Clover isoflavone supplements.
    Laurence G. Howes
    Corresponding author. Tel.: +61 7 55198979; fax: +61 7 55198696.
    1 Previously performed contractual work and been a consultant for Novogen Pty Ltd, a manufacturer of Red Clover isoflavone supplements.
    Department of Cardiology and Cardiovascular Medicine, Griffith University School of Medicine, and Bond University School of Medicine, Gold Coast Hospital, Nerang St., Southport, Qld 4215, Australia
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  • Author Footnotes
    2 Previous employee of Novogen Pty Ltd.
    Jan B. Howes
    2 Previous employee of Novogen Pty Ltd.
    Menopause Solutions Pty Ltd., High St, Southport, Qld 4215, Australia
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  • Author Footnotes
    3 Previously performed consultancy work for Novogen Pty Ltd.
    David C. Knight
    3 Previously performed consultancy work for Novogen Pty Ltd.
    Caroline Chisholm Centre for Women and Children, Liverpool Hospital, Liverpool, NSW 2170, Australia
    Search for articles by this author
  • Author Footnotes
    1 Previously performed contractual work and been a consultant for Novogen Pty Ltd, a manufacturer of Red Clover isoflavone supplements.
    2 Previous employee of Novogen Pty Ltd.
    3 Previously performed consultancy work for Novogen Pty Ltd.



      To perform a systematic review and meta-analysis of all randomized, controlled trials of isoflavone supplementation to determine the efficacy of isoflavone therapy in reducing the number of daily menopausal flushes.


      A comprehensive search of published studies of isoflavone treatment and menopausal flushing was undertaken. Studies were selected if they were randomized, were placebo controlled, provided the number of baseline flushes, the variance in flushes and the reduction in flushes. Effects for isoflavone treatment compared to control were calculated and a meta-analysis was performed. Regression analysis, weighted for the size of the study was performed to investigate the relationship between the dose of isoflavone, or number of baseline flushes and the reduction in flushes achieved compared to control.


      Isoflavone supplementation was found to be associated with a significant reduction in flushes (effect size −0.28, 95% confidence intervals −0.39 to −0.18, P < 0.0001). Marked heterogeneity was found between the studies, but the effect remained significant when analyzed using a random effects model (delta = −0.49, 95% confidence intervals −0.81 to −0.17, P = 0.001). The percentage reduction in flushes was significantly related to the number of baseline flushes per day and the dose of isoflavone studied (β = −0.49 and −0.26, respectively, both P < 0.0001).


      These results suggest that isoflavone supplementation may produce a slight to modest reduction the number of daily flushes in menopausal women and that the benefit may be more apparent in women experiencing a high number of flushes per day.


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