By Matt McMillen
WebMD Health News
Reviewed by Laura J. Martin, MD
Jan. 6, 2012 -- A substance known as the main ingredient of a classic candy may actually be good for your teeth: licorice.
According to a new study in the Journal of Natural Products, licorice root may help keep teeth healthy.
The authors report that compounds found in the dried root of the licorice plant may help prevent and treat tooth decay and gum disease.
But don't rush to the candy aisle. According to information accompanying the study, what's sold as licorice candy in the U.S. is no longer flavored with licorice root but with anise oil.
Chinese licorice root, which is found in northern mainland China, has been a staple in traditional Chinese medicine.
"Licorice is used in many Chinese herbal prescriptions as a guide drug to enhance the activity of other ingredients, reduce toxicity, and improve flavor," the authors write.
However, it has not been tested extensively in the West. According to the National Center for Complementary and Alternative Medicine (NCCAM), clinical trials of an injectable form of licorice root -- not available in the U.S. -- have shown beneficial effects against hepatitis C.
However, the researchers write, "there are not enough reliable data to determine whether licorice is effective for any condition."
This study may help alter that conclusion. That would be good news because tooth decay is the most prevalent chronic disease in the U.S.
According to the National Institute of Dental and Craniofacial Research, an estimated 92% of American adults and seniors have had some form of tooth decay, while 59% of teens and 42% of children aged 11 and under suffer from it.
The Active Ingredients
The two predominant compounds in licorice, licoricidin and licorisoflavan A, were found to be the most effective in inhibiting the growth of cavity-causing bacteria.
These and other compounds found in licorice root were also shown to prevent the growth of bacteria associated with periodontitis, an inflammatory disease that can destroy the bones, gums, and tissue that maintain teeth.
The primary author of the study, Stefan Gafner, PhD, is a researcher with toothpaste producer Tom's of Maine, an independent division of Colgate-Palmolive. Licorice root is an ingredient in some of their products.
Although licorice root extract may prove beneficial, it does come with risks.
According to the NCCAM, it's unknown whether it is safe to take licorice root supplements for more than four to six weeks. Forms of the supplement, which contain glycyrrhizin, can raise blood pressure, lower potassium levels, and cause salt and water retention when taken in large amounts.
People with high blood pressure or heart disease should be cautious when using licorice; pregnant women should avoid taking licorice as a supplement and should not eat large amounts of licorice in food.
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