Black Cohosh Fails to Relieve Menopausal Symptoms
It was no better than placebo for hot flashes and night sweats, study found
TUESDAY, Dec. 19, 2006 (HealthDay News) -- The popular herbal supplement black cohosh is no better than a placebo at relieving hot flashes and night sweats in perimenopausal and postmenopausal women.
That finding from a major study may come as bad news to American women who have been looking for ways to ease menopausal symptoms ever since 2002 research linked hormone replacement therapy (HRT) to a higher risk for breast cancer.
"We were hopeful that black cohosh would prove to be effective for menopause symptoms because options are fairly limited," said the study's lead authoe, Katherine M. Newton of the Group Health Center for Health Studies in Seattle, Wash. "Finding a safe and effective alternative to hormone therapy would have been a tremendous benefit to women," she added.
According to the U.S. National Center for Complementary and Alternative Medicine (NCCAM), black cohosh is made from the roots and stems of a flowering plant also known as black snakeroot or bugbane.
The latest findings, published in the Dec. 19 issue of the Annals of Internal Medicine, came from the Herbal Alternatives (HALT) for Menopause Study, a 12-month randomized, double-blind, placebo-controlled trial in which 351 women ages 45-55 were randomly assigned to one of five interventions: black cohosh; a multi-botanical supplement containing black cohosh and several other herbs; a multi-botanical supplement plus dietary counseling to increase soy consumption; HRT consisting of estrogen with or without progesterone, or a placebo.
Of the five interventions, only hormone replacement therapy effectively reduced menopausal symptoms -- by an average of four symptoms per day -- compared to placebo, the team reported. The other interventions only reduced symptoms by an average of about half a symptom per day.
The study was funded by the U.S. National Institute on Aging and NCCAM.
Newton and her team were midway through the study when the Women's Health Initiative first reported in 2002 that HRT was associated with an increased risk of breast cancer.
To protect participants, "when these findings were released, all women currently in the study were re-consented with this new information and given the option of knowing if they were on hormone therapy," Newton said. "All new participants were given the option of participating without being assigned to hormone therapy. As further information from the Women's Health Initiative was published, we stopped randomization to hormone therapy completely."
Unlike many drug trials that limit participation to women who have at least seven hot flashes per day, Newton's study lowered this threshold to two hot flashes per day. "We wanted to test black cohosh in women with a range of symptoms," she said. "When we looked to see if our findings differed among women with six or less vs. seven or more hot flashes a day, the results were the same."
The results were less conclusive in the soy-intervention group because most participants ended up consuming only one serving of soy per day instead of the recommended two servings per day. "So, it remains possible that a larger increase in soy intake might be of benefit," Newton said.
Dr. Mary Hardy, medical director of integrative medicine at the Ted Mann Family Resource Center at the University of California, Los Angeles, who was not part of the study, said the research was well-designed but had weaknesses.
"The most you can say about this study is that one particular extract of black cohosh doesn't work," she said. "It's very difficult to damn a whole category of herbal products based on one study, because there's so much individual variation in extraction."
And, she added, because the study only used one black cohosh extract -- supplied by New Jersey-based Pure World Inc. -- its results may not be generally applicable.
The two best-studied extracts -- RemiFemin and Klimadynon -- have shown mostly positive results in the treatment of menopausal symptoms, Hardy said. "I have used both of these preparations in my clinical practice and have seen good results. This study has not convinced me to stop prescribing black cohosh for my patients," she added.
In Hardy's experience, black cohosh isn't often as quickly effective as hormone replacement therapy in relieving menopausal symptoms. "But there is a significant clinical response, which is amplified by lifestyle adjustments, such as stress-reduction techniques and avoiding triggers -- such as alcohol and caffeine -- which can make hot flashes worse," she said. "I think herbal interventions are a reasonable choice for women at or around perimenopause because they're generally quite safe."
Because black cohosh doesn't have the estrogenic effects of HRT or the estrogen-like effects of soy, it's unlikely to increase the risk of breast cancer, Hardy said. "To me, soy is not so useful as an adjunct to control hot flashes, although people respond very nicely to it," she said. "It's useful because it's heart-healthy, since cardiovascular risk is something women going through menopause need to worry about."
Newton said that her study doesn't definitively prove that black cohosh is useless in treating menopausal symptoms. "It would be unusual, and perhaps inappropriate, for a single study to completely put the question to rest," she said. "There are currently other well-designed trials being conducted that will add further to the information about black cohosh."
But the study does give women cause for optimism, she added, because it showed that hot flashes usually disappear within four years regardless of treatment.
"Patience and the use of behavioral interventions such as avoiding triggers -- very hot or spicy foods, or alcohol for some women -- keeping a fan or ice water at hand, dressing in layers and sleeping in a cooler room are good options for many women," Newton said.
"For those with intolerable symptoms, we still recommend a discussion with their health care provider about other options," she added.
There's more on black cohosh at the U.S. National Institutes of Health.