Flaxseed May Not Cool Hot Flashes

NEW YORK (Reuters Health) - Despite some promising early evidence, a new clinical trial suggests that flaxseed may not ease menopausal hot flashes after all.

In a study of 188 women, researchers found those who were randomly assigned to eat a daily flaxseed bar saw no more improvement in their hot flashes than women given flax-free "placebo" bars.

Over six weeks, more than one-third of women in each group had a 50 percent reduction in their hot flash "score"—which measures the frequency and severity of a woman's symptoms. The similar results in both groups suggest a placebo effect or some other explanation for the changes some women reported, researchers said.

"What women should take from this study is that there is little compelling information to try flaxseed if the objective is to reduce hot flashes," senior researcher Debra L. Barton told Reuters Health in an email.

In an earlier pilot study, Barton and her colleagues at the Mayo Clinic in Rochester, Minnesota, had found that women who consumed flaxseed did see their hot flashes wane, on average.

But that study had no comparison group of women taking a placebo, Barton pointed out.

Flaxseed is high in compounds called lignans, a type of phytoestrogen. These are plant chemicals structurally similar to estrogen and may have weak estrogen-like (and anti-estrogen) activity in the body.

The most effective treatment for hot flashes is hormone replacement therapy. But since hormones have been linked to increased risks of heart disease, blood clots and breast cancer, many women want alternative hot-flash remedies.

Some antidepressants have been found to cool hot flashes by as much as 80 percent. But "natural" products, Barton noted, have generally failed to stand up to the test of clinical trials. Those products include black cohosh, soy and now flaxseed.