Flaxseed Doesn't Help With Hot Flashes

Women who suffer from hot flashes can mark one more remedy off the list. According to a study reported at the 2011 meeting of the American Society of Clinical Oncology, flaxseed doesn’t reduce the common menopausal symptom as previously thought.

Sandhya Pruthi, MD, a breast health specialist at Mayo Clinic in Rochester, Minn. and one of the co-chairs of the study, says she was surprised at the results of the randomized study because an earlier pilot study indicated flaxseed worked to reduce hot flashes. In the 2007 study, which was widely reported, 30 women who sprinkled two tablespoons of crushed flaxseed on food twice a day reported about a 57 percent reduction in hot flash scores, which were calculated based on the severity and frequency of daily hot flashes, after six weeks.

“I thought it really worked and said we needed to do a controlled, randomized study,” Pruthi says. Because hot flashes can improve over time on their own or with the suggestion that something beneficial was being taken (placebo effect), so a more definitive trial was required. As she designed the larger follow-up study, a few changes were introduced.

“This time we talked to a nutritional company and asked them to put the flaxseed into granola bars because the women in the pilot study didn’t like the texture of the ground seed,” she says.

The current study looked at 188 postmenopausal women, half of the women had a history of breast cancer and half did not. Of the breast cancer survivors, 15 percent were taking an aromatase inhibitor and 25 percent were on tamoxifen. The women were randomized into two groups, one that ate a daily flaxseed bar prepared with 410 milligrams of lignans, the flaxseed component that has estrogenic properties thought to affect hot flashes. The remaining women had granola bars with no flaxseed or lignans. At the end of six weeks, both groups reported about a 36 percent drop in hot flashes.

“There was no significant difference in the reduction of hot flash scores between the two study arms,” Pruthi says. Women in both groups also suffered from gastrointestinal symptoms such as flatulence and diarrhea believed to be due to the fiber content in the granola bars.

“We don’t know why the hot flashes reduced but attribute it to the placebo effect,” Pruthi says, “which is why it is important to conduct controlled studies when evaluating new therapies.”

Pruthi says flaxseed has been studied for other possible uses and anticipates those studies will continue despite the recent evidence that it does little to relieve hot flashes. Pruthi recommends women consider other options for hot flashes such as the antidepressants Paxil (paroxetine) or Effexor (venlafaxine). These anti-depressants have been shown to decrease hot flashes by around 50 to 60 percent, Pruthi says. Another option is the use of Neurontin (gabapentin), an anti-seizure and neuropathic pain medication. However, these options also have side effects that make them undesirable for some women.