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18-09-2011 | Gynaecology | Article

No evidence for hot flash reduction with flaxseed


Free abstract

MedWire News: Women who experience hot flashes during the menopausal transition report no difference in their frequency or severity after taking flaxseed supplements compared with placebo, report researchers.

The finding comes despite previous research that indicates flaxseed could assuage hot flash symptoms in these women, and in women undergoing treatment for breast cancer.

"Women will continue to want to experiment with complimentary therapies, particularly given the recent concerns about breast cancer risk and mortality with hormonal therapy," say Debra Barton (Mayo Clinic, Rochester, Minnesota, USA) and colleagues.

"Clinicians need to be prudent in assessing complimentary 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," they add in the journal Menopause.

A phase II pilot study previously carried out by Barton et al showed that 6 weeks of treatment with crushed flaxseed reduced hot flash scores and frequency in 30 menopausal women. The team therefore carried out a randomized, placebo-controlled phase III trial in similar women to determine whether the supplement was more effective than placebo.

A total of 188 women were recruited in 2009 for the current study, of whom 146 had sufficient data for analysis. The researchers evaluated the effect of flaxseed (versus placebo) on hot flash activity, activity interference from hot flashes, mood, and other menopausal symptoms. All women had been experiencing hot flashes for more than 1 month at a frequency of 28 or more times per week before enrollment into the study.

Flaxseed was given in a bar format, containing 7.5 g of flaxseed (5% lignans - the active ingredient), 6 g protein, and 20% fiber. The placebo bar contained 2 g protein, 20% fiber, and no flaxseed, lignans, or soy products.

The women completed a baseline flaxseed-free week during which they kept a diary of their hot flashes, followed by 6 weeks of one bar per day, also recorded with a hot flash diary. The women reported on other measures, including the Hot Flash Related Daily Interference Scale and the Profile of Mood States.

Overall, Barton and co-investigators report no significant differences in the reduction of hot flash scores between study arms during the 7-week period. Both arms experienced a similar reduction in hot flash scores, with a nonsignificant mean change from baseline of -4.9 and -3.5 for women taking flaxseed and placebo, respectively.

Similarly, the reduction in frequency of hot flashes was not significantly different per treatment group, at 29% versus 28% for the flaxseed- and placebo-takers, respectively.

Of note, the flaxseed group did report more abdominal distention, flatulence, and nausea, while the placebo group reported more diarrhea, however these differences were not significant.

None of the scales of mood disturbance showed any significant difference according to supplementation type.

Only a minority of alternative therapies aimed at treating menopausal symptoms have been studied in a rigorous, randomized, controlled setting, note Barton and team. And none have been proven to be effective, they add.

"This supports that caution is needed regarding the use of popular herbs/dietary supplements for hot flashes and general menopausal symptoms that have not been studied using rigorous trial designs," concludes the research team.

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Sarah Guy

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