U.S. flag

An official website of the United States government

Dot gov

The .gov means it's official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

National Toxicology Program

National Toxicology Program

UPDATE NewsletterUPDATE NewsletterJuly 2016

Research on botanicals takes center stage at community event

By Ernie Hood
Reprinted from Environmental Factor

Genetic toxicologist Stephanie Smith-Roe, Ph.D., discussed National Toxicology Program (NTP) research on botanicals at a May 31 community event. Botanicals are considered dietary supplements, so they are regulated by the U.S. Food and Drug Administration as food products.

Smith-Roe was the second NTP scientist (see related story) to be featured at the monthly pizza lunch sponsored by American Scientist magazine; the Research Triangle Park (RTP), North Carolina, chapter of the scientific research society Sigma Xi; and the Science Communicators of North Carolina. The talk attracted about 40 science buffs to The Frontier in RTP, not far from the NIEHS campus.

Communicating science to the public is of particular interest to Smith-Roe. She is also president of the Genetics and Environmental Mutagenesis Society, whose spring meeting was focused on science communication and outreach.

Case study: black cohosh extract

To illustrate the scientific concepts behind NTP evaluation of botanicals, Smith-Roe presented a case study on black cohosh extract, promoted in various forms to women as a remedy for the symptoms of menopause, premenstrual syndrome, and menstrual cycle irregularity. Black cohosh extract, a complex chemical mixture made up of more than 100 compounds, is one of the most popular botanical products on the market, with U.S. sales of about $42 million in 2014, according to Smith-Roe.

“Little is known about the safety and efficacy of botanicals,” she said. “Due to public concern, NTP has been studying botanicals for the past 20 years, specifically to fill in data gaps on safety.” NTP recently hosted a workshop on the challenges of studying botanicals.

NTP found that black cohosh extract was not toxic to the reproductive system of rats and mice in 90-day studies, nor did it affect estrogenic signaling, despite the marketed uses of black cohosh extract. “It does contain salicylic acid, and dopaminergic and serotonergic compounds, which could account for why some consumers feel some level of relief from taking this botanical,” Smith-Roe noted. Dopamine helps control the brain's reward and pleasure centers, while serotonin is responsible for maintaining mood balance.

Additional 90-day studies in rodents revealed dose-dependent formation of micronuclei, which are a telltale sign of chromosome damage. Scientists suspect that the extract may interfere with folate metabolism, which is vital for cell division and equilibrium within the body.

NTP researchers are now conducting a 2-year rodent cancer study. Smith-Roe initiated the study by using an in vitro assay to demonstrate that more than a dozen black cohosh extracts and powders from different suppliers induced micronuclei in human cells. “Taken together, these data suggest that there is a chemical, or perhaps more than one chemical, in the root of the plant that is genotoxic [or damaging to DNA],” she said.

Clinical study recruiting

What do these findings mean for women taking black cohosh? To find out, NTP partnered with the NIEHS Clinical Research Unit to initiate the Black Cohosh Study.

The clinical study will investigate the effects of black cohosh dietary supplements on women who have been taking it for at least three months. The study is currently seeking participants.

(Ernie Hood is a contract writer for the NIEHS Office of Communications and Public Liaison.)

Black Cohosh Flower and Root

Black cohosh (Actaea racemosa), a member of the buttercup family and native to North America, was nominated for study by the National Cancer Institute and NIEHS. The extract is made from the roots, right. (Photo courtesy of Stephanie Smith-Roe)

Back to Top

The Update Newsletter is produced by NTP Office of Policy, Review, and Outreach. The text is not copyrighted and can be reprinted without permission. If you use parts of the Update Newsletter in your publication, we ask that you provide us with a copy for our records. We welcome your comments and suggestions.

Director of Office of Policy, Review, and Outreach and Editor-in-Chief: Mary Wolfe | Managing Editor: Anna Lee Mosley