Flaxseed No More Effective Than Placebo for Hot Flashes

CHICAGO—Flaxseed failed to have a significant effect on reducing hot flashes in women compared with placebo, according to results of a randomized, placebo-controlled trial supported by the North Central Cancer Treatment Group. The study included breast cancer survivors as well as women who had never had breast cancer who experienced frequent hot flashes throughout the day and night.

These results were disappointing, said lead investigator Sandhya Pruthi, MD, Mayo Clinic, Rochester, Minnesota. “Hot flashes are bothersome, and although there are effective therapies, these have side effects. We need to balance side effects with efficacy. Although the present study was disappointing, we need to continue to try to identify complementary treatments [with fewer side effects] that can relieve hot flashes,” she said at a presentation.

Hot flashes compromise quality of life. They can be socially awkward as well as interfere with sleep. At present, there are 2 effective options for treatment of hot flashes—venlafaxine and gabapentin—but both have side effects that may not be acceptable. After hearing anecdotal evidence that flaxseed controlled hot flashes, Pruthi and colleagues conducted a pilot study in 30 women with hot flashes, and results showed that flaxseed decreased both the severity and frequency of hot flashes. That pilot trial led to the randomized, placebo-controlled trial.

The current study enrolled 188 participants who experienced >28 hot flashes per week at baseline; 75% were aged 50 years and older; 51% had a history of breast cancer. Among women with a breast cancer history, 15% were taking an aromatase inhibitor and 25% were taking tamoxifen. Patients were randomized to 1 flaxseed bar per day containing 410 mg lignans and fiber or to 1 placebo bar per day with 2 g protein and fiber; treatment was continued for 6 weeks.

The flaxseed bars achieved a 33% decrease in hot flash score from baseline compared with a 29% decrease for placebo bars. Mean hot flash scores were reduced by 4.9 units in the flaxseed group and 3.5 units in the placebo group. This difference between treatment arms was not significant, Pruthi said. In both groups, about one third of the women received a 50% reduction in their hot flashes.

No significant differences in toxicity were observed between the 2 arms. Abdominal distension, gas, and diarrhea were common in both arms, presumably as a result of fiber content, she said.

“As oncologists, we need to deal with the rollercoaster effects of our research. [Some trials appear promising and then pan out not to have efficacy.] Hot flashes have a negative impact on quality of life and we need to find the most effective treatment. There are some effective treatments for hot flashes. Patients should discuss treatment options with their doctors,” said Mark G. Kris, MD, chief of Thoracic Oncology Service at Memorial Sloan-Kettering Cancer Center in New York City, who moderated the press conference where Pruthi presented the results.