Flaxseed Does Not Reduce Hot Flashes

If you are a woman who suffers with hot flashes, do not count on flaxseed to provide much relief. That’s the word from investigators at Mayo Clinic and North Central Cancer Treatment Group (NCCTG) who conducted a phase III clinical trial among postmenopausal women.

Flaxseed has other health benefits

It’s estimated that 40 to 90 percent of women entering menopause experience hot flashes, and that up to 85 percent of women suffer with them after menopause. Women who have undergone treatment for breast cancer also experience this side effect, which are also referred to as hot flushes and night sweats.

Hot flashes are thought to be caused by hormonal changes that occur with aging, especially as a woman’s estrogen levels decline. The feeling of heat is related to a disorder in how the body controls and regulates its temperature (thermoregulation), but exactly how changing hormone levels affect thermoregulation is not known.

Previous research in 2007 had suggested that consuming 40 grams of crushed flaxseed per day might relieve hot flashes. The new study, a placebo-controlled randomized trial, explored the efficacy of flaxseed in reducing hot flashes in postmenopausal women.

A total of 188 women were enrolled in the trial, which lasted from October to December 2009. The women were randomly assigned to consume a flaxseed bar (containing 410 mg of lignans) or a placebo bar for six weeks. Lignans are chemical compounds belonging to a class called phytoestrogens, which are estrogen-like substances. Flaxseed is a rich source of lignans.

The study participants kept a record of their hot flashes during the study. After six weeks, hot flashes declined by 4.9 units among women who had consumed flaxseed bars compared with 3.5 in the placebo group. Slightly more than one-third of women in both groups experienced a 50 percent reduction in hot flash scores.

Side effects were reported by women in both groups, including abdominal distention, diarrhea, flatulence, and nausea. The study’s authors noted that the side effects were probably related to the fiber content in both the flaxseed and placebo bars.

The study’s findings were presented at the American Society of Clinical Oncology Annual Meeting in Chicago. Sandhya Pruthi, MD, of Mayo Clinic’s Breast Diagnostic Clinic and a researcher with NCCTG, noted that women should not stop using flaxseed if they like it because it offers beneficial fiber and may also help lower cholesterol.

The authors concluded that their results did not support the use of flaxseed lignans for relieving hot flashes. These findings support an earlier study that used only 46 mg of flaxseed lignans daily for 12 weeks.

SOURCES:
American Society of Clinical Oncology
Simbalista RL et al. Journal of Nutrition 2010 Feb; 140(2): 293-97