Black Cohosh Does Not Relieve Symptoms of Menopause

The popular dietary supplement black cohosh does not lessen hot flashes caused by menopause, according to results of a recently released clinical trial.

The study was a randomized, controlled trial, which is the scientific “gold” standard for assessing the therapeutic value of drugs – or in this case, dietary supplements. It compared several herbal supplement regimens over a period of 12 months and included 351 women ages 45 to 55 years who were approaching menopause. The results of this large trial, called the Herbal ALTernatives for Menopause Study (HALT), were published in the December 19, 2006, Annals of Internal Medicine.

The trial, conducted by researchers from the Group Health Center for Health Studies and the University of Washington, was co-sponsored by the National Institute on Aging and the National Center for Complementary and Alternative Medicine, which are both components of the National Institutes of Health (NIH).  

Study compares treatments
The 351 women who participated in the trial were randomly assigned to one of five treatment groups:

1. Black cohosh
2. A multi-ingredient supplement containing black cohosh, alfalfa, boron, chaste tree, dong quai, false unicorn, licorice, oats, pomegranate and Siberian ginseng.  
3. Diet counseling to increase soy intake plus the multi-ingredient supplement.
4. Prescription hormone replacement therapy of estrogen alone (PREMARIN) or estrogen plus medroxyprogesterone (PREMPRO).
5. An inactive placebo, containing no drug or dietary supplement.

At the beginning of the study, women in each of the five treatment groups had experienced between six and seven hot flashes and about two episodes of night sweats per day. Table 1 lists the average number of hot flashes and night sweats for the women in the five treatment groups. As can be seen, the symptoms in the five groups were quite similar before the treatments.

Table 2 lists the average change in both the symptoms of hot flashes and night sweats compared to the placebo. The minus sign (-) indicates a decrease in the average number of menopausal symptoms. The plus sign (+) indicates an increase in menopausal symptoms. The differences in symptoms were not statistically significant for any of the first three treatment groups: black cohosh, multi-ingredient supplement or soy food counseling.

The researchers concluded that:

Black cohosh used in isolation, or as part of a multibotanical regimen, shows little potential as an important therapy for relief of vasomotor symptoms [change of the size of blood vessels responsible for hot flashes].

Dietary supplement industry inadequately controlled
Previous studies have also found that black cohosh does not provide short-term benefits in the treatment of menopausal symptoms.

However, this dietary supplement remains widely promoted and sold because supplements are not required to prove their safety and effectiveness through a regulated process managed by the Food and Drug Administration (FDA), as is required by over-the-counter and prescription drugs. Supplements are exempt from this measure of consumer protection because of the Dietary Supplement Health and Education Act (DSHEA) passed in 1994, a deeply flawed law that allows dietary supplement producers to operate outside FDA drug regulations.

Black cohosh was listed as a Do Not Use product in the 2005 edition of Worst Pills, Best Pills because of the lack of regulation of dietary supplements in the United States and questionable evidence of effectiveness in the published literature. In addition, there is now evidence that black cohosh is toxic to the liver (see Worst Pills, Best Pills News August 2006).

The symptoms of potential liver toxicity are listed below.  If any of these develop while taking black cohosh, seek medical attention immediately:

• Itchy skin
• Jaundice (yellowing of the skin or whites of the eyes)
• Dark urine
• Tenderness in the location of the liver, which is the upper right side of the abdomen  
• Unexplained “flu-like” symptoms

Long-term risks of post-menopausal hormone replacement outweigh potential benefits
Table 2 demonstrates that the HALT study showed a statistically significant decrease in hot flashes and night sweats with the treatment group receiving the prescription drug estrogen with or without medroxyprogesterone.

The large decrease in the average number of symptoms seen in women taking estrogen with or without medroxyprogesterone is expected. The short-term use of estrogen is very effective for the management of menopausal symptoms. This is the only FDA-approved use for estrogen in post-menopausal women, though it comes with significant risks.

In 2002, the results of the Women’s Health Initiative’s (WHI) large government-sponsored study showed that the harms from long term post-menopausal hormone replacement treatment outweighed any suspected benefits, such as reducing the risk of heart disease or Alzheimer’s disease (see Worst Pills, Best Pills News September 2002). As a result of the WHI study, the numbers of prescriptions for estrogens reportedly declined from 91 million in 2001 to 57 million in 2003. This may be the reason for an important decline in the incidence of breast cancer seen in 2003 in the United States.

At the 29th annual San Antonio Breast Cancer Symposium, researchers reported an overall seven percent decline in the incidence of breast cancer between 2002 and 2003. Researchers estimated that as many as 14,000 new cases of breast cancer were averted.

This decline was linked to the decreased number of estrogen prescriptions.

The WHI results opened up new marketing opportunities for peddlers of all kinds of unproven treatments for menopausal symptoms, including dietary supplements such as black cohosh and so-called bioidentical hormones pushed by compounding pharmacists (see Worst Pills, Best Pills News August 2006).  

What You Can Do
You should not use products containing black cohosh. There is reliable evidence that this herb does not help menopausal symptoms compared to no treatment at all and there is growing evidence of substantial harm with the use of black cohosh.