A Phase III, randomized, placebo-controlled, double-blind trial of flaxseed for the treatment of hot flashes: North Central Cancer Treatment Group N08C7

January 1, 2011 Human Health and Nutrition Data 0 Comments

A Phase III, randomized, placebo-controlled, double-blind trial of flaxseed for the treatment of hot flashes: North Central Cancer Treatment Group N08C7

Year: 2011
Authors: Pruthi, S. Qin, R. Terstreip, S.A. Liu, H. Loprinzi, C.L. Shah, T.R.C Tucker, K.F. et. Al.
Publication Name: Menopause
Publication Details: Volume 19; Number 1; Pages 000-000.


Preliminary data suggest that flaxseed, a rich source of dietary lignans, may be a potentially effective treatment of hot flashes. A phase III, randomized, placebo, controlled trial was conducted to evaluate the efficacy of flaxseed in reducing hot flashes. Postmenopausal women with or without breast cancer were randomly assigned to a flaxseed bar (providing 410 mg of lignans) for 6 weeks versus a placebo bar. Participants completed daily, prospective, hot flash diaries during the baseline week, and then ate one study bar per day for 6 weeks while recording their daily hot flashes. The intra-participant difference in hot flash activity between baseline and the last treatment week was the primary endpoint. Adverse effects were evaluated through a self-report and the Common Terminology Criteria assessment. A total of 188 women were enrolled in this trial. The mean hot flash score was reduced 4.9 in the flaxseed group and 3.5 in the placebo group (P = 0.29). In both groups, slightly more than a third of the women received a 50% reduction in their hot flash score. Only one adverse effect was significantly different between groups, grade 1 pruritus, which was more common in the placebo group (8% vs 1%). Both groups reported abdominal distension, flatulence, diarrhea, and nausea. Adherence and ability to detect treatment assignment did not differ between groups. The results of this trial do not support the use of 410 mg of lignans for the reduction of hot flashes. The bars were fairly well tolerated, with both groups reporting gastrointestinal effects, probably due to the fiber content. (Author's abstract)
Hot flashes are experienced by up to 75% of women as they go through the menopausal transition. Hot flashes are not just a physiologic phenomenon but are also accompanied by, and associated with, psychologic experiences. One dietary treatment, flaxseed, has shown promise in at least one pilot trial to relieve hot flashes.  Flaxseed and its lignans may have potent anti-estrogenic effects on estrogen receptor Y positive breast cancer and may have benefits in breast cancer prevention efforts. Based on mixed pilot data suggesting that flaxseed may reduce hot flashes, a phase II, open-label trial with 1 week of baseline and 6 weeks of treatment with flaxseed involving 30 evaluable women, was conducted to evaluate its impact on hot flash reduction. Participants received 40 g of flaxseed (1% secoisolariciresinol diglucoside), which represents 400 mg of lignans.  The pilot data demonstrated a mean decrease in hot flash scores of 57% and a mean reduction in daily hot flash frequency of 50%, from 7.3 to 3.6 hot flashes per day. The reduction in hot flash score and frequency was greater than what would be expected with a placebo. As a result, this study was  implemented to evaluate flaxseed versus placebo for hot flash reduction.  This trial delivered a large dose (410 mg) of lignans which did not reduce hot flashes more than a placebo.  Hot flash reductions were seen at weeks 6 and 7, which suggests that had the duration fo the study been longer, significance may have been seen, and women with higher numbers of hot flashes at baseline experienced greater reductions.  The authors conclude that, from a clinical standpoint, women will continue to want to experiment with complementary therapies, particularly given the recent concerns about breast cancer risk and mortality with hormonal therapy. Clinicians need to be prudent in assessing complementary therapy use by their patients and educate women who are seeking alternative therapies about the known risks, benefits, and limitations of the evidence to date. (Editor's comments).

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