A randomized, Phase III trial showed that flaxseed did not reduce hot flashes in postmenopausal women who reported experiencing at least 28 hot flashes per week. The trial included women with and without a history of breast cancer.

"The results were surprising. Pilot study data suggested that flaxseed use was associated with reduction in hot flashes," said lead author Sandhya Pruthi, PhD, associate professor of medicine at the Mayo Clinic in Rochester, Minnesota. "Flaxseed may be a highly touted supplement for many ills, but according to our randomized study results, it is not effective for hot flashes."

Hot flashes, a common symptom during menopause or following hormonal breast cancer treatment, can have a serious effect on quality of life. Though oestrogen therapy may be effective for reducing hot flashes, many women are wary of the cancer risks associated with hormonal therapy. Preliminary evidence suggested that flaxseed might have weak anti-oestrogen properties, and a previous pilot study by the authors showed a 57 percent reduction in hot flashes in women taking flaxseed.

In this study, 188 postmenopausal women were randomly assigned to eat a daily flaxseed bar that contained 410 mg of lignans, a plant-based compound known to have both oestrogenic and anti-oestrogenic effects (88 women), or placebo, a bar made of protein and fiber without flaxseed or lignans (90), for six weeks. Of the 178 evaluable women in the study, 91 had a history of breast cancer while 87 did not.

They completed a daily diary of their hot flashes, and the researchers measured the differences in hot flashes – in number and severity – between the start and completion of the study. Anti-oestrogen drugs such as tamoxifen, raloxifene or aromatase inhibitors were allowed if the women had been on a consistent dose for more than four weeks and were planning on remaining on the medication during the study period.

The investigators found little difference between the two groups. In both groups a little more than one-third of the women had a 50 percent reduction in hot flash scores. Both groups reported increased bloating, diarrhea and nausea.


Source: ASCO

Reference:  Abstract: CRA9015 The evaluation of flaxseed for hot flashes, results of a randomized, controlled trial, NCCTG study N08C7. S. Pruthi, R. Qin, S. A. Terstriep, H. Liu, C. L. Loprinzi, T. R. C. Shah, K. F. Tucker, S. R. Dakhil, M. J. Bury, R. L. Carolla, P. D. Steen, J. Vuky, D. L. Barton.