Flaxseed is no help for hot flashes, study finds

Flaxseed is widely believed to reduce the incidence and severity of hot flashes, both those resulting from menopause and those caused by estrogen-deprivation therapies in the treatment of breast cancer. But a new clinical trial has found that daily consumption of flaxseed is no more effective than a placebo in blocking symptoms, researchers reported Sunday at a Chicago meeting of the American Society of ClinicalOncology.

The results were “surprising,” lead author Sandhya Pruthi of the Mayo clinic in Rochester, Minn., said, because a preliminary trial she conducted appeared to show benefit. That initial study, however, was not placebo controlled.

Flaxseed is thought to be beneficial because it contains phytoestrogens, chemicals produced by plants that mimic the effects of mammalian estrogen.

Pruthi and her colleagues enrolled 188 women, about half of whom had a history of breast cancer and half with menopausal symptoms. All reported having at least 28 hot flashes per week. Half were assigned to eat a daily flaxseed bar for six weeks and half a similar bar containing no flaxseed. About a third of the women in each group reported a 50% reduction in symptoms, but there were no statistical differences in symptom changes between the two groups.


Both groups also suffered bloating, diarrhea and nausea, which the researchers attributed to the high amount of fiber in both types of bars.

“Flaxseed may be a highly touted supplement for many ills,” Pruthi said in a statement, “but according to our randomized study results, it is not effective for hot flashes.”