Evaluating flaxseed to treat hot flashes

Hot flashes are a common symptom during the menopause transition or following breast cancer treatment.

During the American Society of Clinical Oncology meeting, researchers at various centers in the US reported their findings.

First, the details.

  • 188 postmenopausal women were randomly assigned to a treatment group for 6 weeks.
    • Flaxseed bar (providing 410 mg of lignans)
    • Placebo bar.
  • A lignan is a phytoestrogen found in the hulls (dry outer covering) of flax seed.
  • Participants reported their hot flashes and any side effects.

And, the results.

  • Average hot flash scores were reduced by 4.9 units in the flaxseed group and 3.5 in the placebo group — not a significant difference.
  • In both groups, a little over a third of the women received a 50% reduction in their hot flash scores.
  • Only one side effect was significantly different between groups — grade 1 pruritus — which was more common in the placebo group (7%) vs the flaxseed group (1%).
  • Both groups reported increased abdominal distension, flatulence, diarrhea, and nausea.
  • Adherence and ability to detect treatment assignment did not differ between groups.

The bottom line?

The authors concluded, “The results of this trial do not support the use of 410 mg of flaxseed lignans for the reduction of hot flashes.”

“The gastrointestinal side effects seen in both groups were likely due to the fiber content in the flaxseed and placebo bars.”

Last year, researchers from Sao Paulo, Brazil reported, “Although flaxseed is safe, its consumption at this level (46 mg lignans/day) is no more effective than placebo for reducing hot flashes.”

These findings contradict an early preliminary study where researchers from the Mayo Clinic reported reduced hot flashes with dietary therapy that included flaxseed 40 grams daily.

6/11/11 21:33 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.