Licorice roots have a diverse and flavorful history, having been used in ancient Egyptian times as a tea and in traditional Chinese medicines, all the way to today as a flavoring agent and as an ingredient in some licorice candies. Some women now take licorice extracts as supplements to treat hot flashes and other menopausal symptoms. But scientists caution that the substance could pose a health risk by interacting with medications.
The researchers are presenting their results today at the 254th
National Meeting & Exposition of the American Chemical Society
(ACS). ACS, the world's largest scientific society, is holding the
meeting here through Thursday. It features nearly 9,400 presentations on
a wide range of science topics.
"Concerns about the risk of stroke and breast cancer associated with
conventional hormone therapy are prompting women to seek alternatives,"
Richard B. van Breemen, Ph.D., says. "Some take botanical dietary
supplements, such as licorice, to treat menopausal symptoms like hot
But just because a substance is sold as a supplement in a health
food store doesn't mean it is completely safe for all people to take.
And on its own, even as a candy, licorice can be harmful in some cases.
The U.S. Food and Drug Administration recommends that licorice not be
eaten in large amounts during one sitting, and warns that excessive
consumption can lead to irregular heart rhythm and muscle fatigue.
"Consuming too much licorice can be harmful, but in our lab, we
wondered whether the small amounts in dietary supplements might also
cause problems by interfering with drug metabolism or transportation,"
says van Breemen, who is at the University of Illinois at Chicago. "The
liver has enzymes that process medications, and if these enzymes are
induced or inhibited, the drugs will either be processed too quickly or
too slowly, respectively." He points out that these changes could pose a
significant safety risk to those who take a daily licorice dietary
supplement along with other medication.
Van Breemen's team analyzed how three types of licorice -- two North American species, Glycyrrhiza uralensis and G. inflata, and a European species called G. glabra
-- affected liver enzymes involved in drug metabolism. They found that
all three species inhibit several of these enzymes. Only G. uralensis and G. inflata extracts were found to induce some of these enzymes. Therefore, the researchers say that G. uralensis and G. inflata are more likely to interfere with drug metabolism when compared to G. glabra.
Consumers would have a difficult time using this information,
however, because most supplements don't list the species on their
labels. But the researchers are using this knowledge to develop their
own licorice therapy that would be safe and effective for women
experiencing menopausal symptoms, such as hot flashes. They plan to
start clinical trials on their G. glabra-based supplements next year.