At a meeting of the American Association for Cancer Research held in Washington , D. C., (July 11, 2003), Vicki Davis of Duquesne University in Pittsburgh, found that feeding black cohosh to mice susceptible to breast cancer, more than doubled their chances of having the breast cancer spread to their lungs. This is frightening because black cohosh contains plant estrogens that are supposed to help prevent breast cancer by blocking stimulation of breast cancer cells.

This does not mean that black cohosh causes breast cancer to spread. It tells us that we don't know as much about plant estrogen as we think we do. In July 2002, the National Institutes of Health announced that they would stop a major clinical study in postmenopausal women taking estrogen with progesterone because of increased risk for breast cancers, heart attacks, strokes, and blood clots, even though those taking these hormones had far fewer hip fractures and colon cancers. That report stopped most doctors from prescribing estrogen to postmenopausal women.

At the same time, an article in the medical journal, Alternative Therapies in Health and Medicine, showed that Remifemin, an extract from the black cohosh plant, effectively controls menopausal depression and hot flushes. So, many people felt that we had a safe alternative to estrogen after the menopause, and today, this multi-million dollar herbal product is sold by one of the largest drug companies in the world, GlaxoSmithKlein. This new study suggests that it may not be as safe as we thought.

Black cohosh: Efficacy, safety, and use in clinical and preclinical applications. Alternative Therapies in Health and Medicine, 2001, Vol 7, Iss 3, pp 93-100. DJ McKenna, K Jones, S Humphrey, K Hughes. McKenna DJ, Inst Nat Prod Res Marine, St Croix, MN USA

Checked 9/5/05

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