Licorice Root for Tooth Decay, Gum Disease, and Oral Health

Updated on September 24, 2018
AliciaC profile image

Linda Crampton has an honors degree in biology. She is very interested in the production of medicines from chemicals in nature.

Licorice root is edible, sweet, and delicious.
Licorice root is edible, sweet, and delicious. | Source

The Licorice Plant

Licorice is a perennial herb in the legume family—the same family to which peas and beans belong. The root of the plant is edible and is both sweet and flavorful. In addition to being eaten whole and chopped, it can be boiled in water to make an extract. This extract can be concentrated and added to foods and drinks or used to make candy, sometimes in combination with other substances. The word "licorice" is used to refer to the plant, the extract, or the candy. In the UK, the word is spelled "liquorice".

Licorice has been a popular food additive since ancient times. It's also had a long use in traditional medicine. Today it's claimed to have many health benefits. There is preliminary evidence supporting some of these claims, but for others the evidence is mixed. Research suggests that licorice may be very beneficial for oral health, however. It appears to inhibit the activity of bacteria that cause tooth decay and gum disease.

Although the future role of licorice in oral hygiene looks promising, there are potential dangers to ingesting the root or extract, especially for some people. Anyone who eats or drinks the products or who uses them in the hope of improving dental hygiene needs to be very aware of these dangers.

Leaves of a licorice plant (Glycyrrhiza glabra)
Leaves of a licorice plant (Glycyrrhiza glabra) | Source

The scientific name of the licorice plant is Glycyrrhiza glabra. It's a member of the family Fabaceae, which is also known as the Leguminosae or the Legume family. Peas, beans, lentils, and peanuts also belong to this family. The members of the family have compound leaves and a fruit in the form of a legume or a pod.

Two Antibacterial Compounds in Licorice Root

Two antibacterial chemicals in licorice root are licoricidin and licorisoflavan A. In 2012, an international research team made some interesting discoveries that linked these chemicals to oral health. The results were published by the American Chemical Society.

The researchers found that each chemical strongly inhibited two major tooth decay bacteria—Streptococcus mutans, which is the most important bacterium involved in human tooth decay, and Streptococcus sobrinus. The chemicals also had a major inhibitory effect on two common gum disease bacteria—Porphyromonas gingivalis and Prevotella intermedia. In addition, the licoricidin moderately inhibited a third bacterium, Fusobacterium nucleatum, which is often associated with periodontal disease.

The scientists used an extract made from licorice root and tested it on bacteria that were placed in lab containers. Hopefully the chemicals obtained from the root will have the same effect in our mouths as they did in the lab. If they do, we'll need to find out how much licorice needs to be used and how long it will have to stay in contact with oral bacteria to inhibit their growth.

Streptococcus mutans is a common cause of tooth decay.
Streptococcus mutans is a common cause of tooth decay. | Source

Trans-Chalcone and Oral Bacteria

In 2015, researchers at the University of Edinburgh examined another antibacterial compound in licorice. The researchers tested the effect of a chemical called trans-chalcone on oral bacteria. The news release from the university refers to the potential benefit of natural products for oral health, but it also says that the trans-chalcone was "related" to chemicals in licorice root. This presumably means that a natural substance was slightly altered. Even before the experiment was performed, scientists knew that licorice root contains chemicals called chalcones and that these have antibacterial properties.

The researchers found that trans-chalcone blocks an enzyme needed by Streptococcus mutans when it forms biofilms. A biofilm is a collection of bacteria embedded in a protective polysaccharide layer. Biofilms in the mouth are known as plaque. Bacteria in biofilms are much harder to attack than those outside biofilms.

The research is very interesting, but once again it was performed in lab equipment instead of in the human mouth. Lab results are sometimes the same as the results in humans, but not always. Two problems with the use of licorice products for oral health are that materials in the mouth are diluted by saliva and they are quickly swallowed. Researchers at the University of Michigan may have a solution to this problem. They used a licorice lollipop in their research project. Since the lollipop was repeatedly sucked, potentially beneficial compounds were continually added to the mouth.

Flowers of a licorice plant
Flowers of a licorice plant | Source

Licorice Lollipops and Oral Bacteria

In a pilot study, researchers at the University of Michigan gave a small group of children sugar-free lollipops that contained a licorice extract. They found that when children at high risk for cavities sucked two lollipops a day for three weeks, the level of Streptocococcus mutans in their saliva was greatly decreased. The bacterial population stayed at a decreased level for twenty-two days after the last lollipop was sucked and then began to increase again.

In another pilot study using lollipops, the licorice extract in the candy was rich in a substance called glycyrrhizol A. In this study, people of different ages sucked two lollipops a day for ten days. Many of the people (but not all of them) showed a big decrease in Streptococcus mutans in their saliva after the treatment.

Other research suggests that licorice root extracts can reduce the inflammation involved in periodontal disease and even inhibit the bone loss that occurs in the disease. They could be very helpful for improving oral health.

The amount of licorice root that can be safely tolerated depends on body weight as well as pre-existing health conditions and life stage. Pregnant and nursing women and people with estrogen-sensitive diseases shouldn’t eat licorice.

Potential Dangers of Licorice Root Products

Black and red licorice candy rarely contain real licorice extract. They’re generally flavored with anise oil and/or artificial flavors instead of licorice. They contain a lot of sugar too, which is bad for oral health. Both licorice and anise seeds get much of their flavor from a chemical called anethole.

Real licorice candy and products are available, but caution is needed before a person starts eating or drinking these. Licorice affects blood pressure by increasing the amount of a hormone called aldosterone in the blood. Aldosterone stimulates water and sodium reabsorption in the kidneys and also stimulates potassium excretion. An excessive amount of aldosterone raises blood pressure and may lead to heart problems. It may also cause muscle weakness.

Licorice contains isoflavones, which are phytoestrogens, so it may affect the function of hormones in the body. Some evidence suggests that it lowers the testosterone level in men. Another potential problem with ingesting the substance is that it may interfere with the action of certain medications.

Black licorice may not contain real licorice extract and may not be tooth-friendly.
Black licorice may not contain real licorice extract and may not be tooth-friendly. | Source

The European Scientific Committee on Food advises that regular glycyrrhizin doses of 100 mg/day present a risk to health, and advocate a safe average daily intake of no more than 10 mg/person/day. This is an amount equivalent to less than half a cup of liquorice tea or just 6 g of liquorice confectionary daily.

— Allcock, E. and Cowdery, J, British Medical Journal

Recommended Limits

The consensus of health experts seems to be that for most people licorice is safe when used occasionally and in moderate amounts to flavor foods or drinks or to eat as a treat. The maximum amount that is safe depends on an individual's state of health. As mentioned above, some people shouldn't eat the substance at all.

People over forty who have heart disease seem to be most susceptible to health problems caused by the root or extract. Even children may be adversely affected by licorice, however, as the video below shows.

Several researchers say that up to five or six grams of licorice a day is probably safe for healthy adults. They also say that five grams a day may be too much for people who have heart disease or kidney problems, however. It seems advisable to use considerably less than this amount when using licorice for oral health, even when a product is being used as a mouthwash.

Healthy people should follow the recommended limits above and should also look at the WHO recommendations below, which are slightly different. People who have health problems such as heart or kidney problems or high blood pressure should ask their doctor about the advisability of eating, drinking, or using licorice products.

The World Health Organization (WHO) recommends a maximum intake of 2 mg glycyrrhizic acid per kg of body weight per day. The organization says this intake is unlikely to cause adverse effects, although negative effects are still possible in sensitive people. Licorice is assumed to contain 0.2% glycyrrhizic acid by weight.

Deglycyrrhizinated Licorice

Glycyrrhizin (or glycyrrhizic acid) is the main chemical responsible for the sweetness of licorice. It also seems to be responsible for many of the potentially dangerous effects of the substance. The boy described in the video above had eaten twenty licorice candies a day for four months before his seizures. This gave him a daily dose of 2.88 mg of glycyrrhizic acid per kg of body weight, which is significantly higher than the upper limit recommended by the World Health Organization.

Deglycyrrhizinated licorice products (DGL products) are available in stores. These products have had their glycyrrhizin removed and may therefore be safe. It's not known if ingesting DGL instead of whole licorice eliminates every dangerous effect or has all of the health benefits that are attributed to the whole substance.

A Licorice Poll

Do you eat licorice?

See results
A licorice plant
A licorice plant | Source

Oral Health Now and in the Future

Anything that decreases tooth decay and gum disease and is also safe to use would be a great addition to an oral hygiene routine. Oral hygiene products that are flavored with licorice root or extract already exist, but it’s unknown if they contain enough of the helpful chemicals to affect bacteria in the mouth.

Perhaps in the future we’ll be able to buy mouthwashes containing effective amounts of the antibacterial chemicals from licorice root (assuming their ability to fight oral bacteria is confirmed by more research). We may also be able to buy toothpaste and chewing gum that contain useful amounts of the chemicals. Until then, we need to be careful when eating or drinking products containing them. It would be a good idea to keep track of the amount of licorice that we’re ingesting or using in order to prevent any health problems from developing.

References

Dried licorice root fights oral bacteria from the American Chemical Society

Trans-chalcone and oral bacteria from the University of Edinburgh

Licorice lollipops and oral health from the European Archives of Paediatric Dentistry (abstract and preview)

Black licorice warning from the FDA (Food and Drug Administration)

Elsevier. (2015, March 2). Licorice manufacturers encouraged to state daily limit of consumption. ScienceDaily. Retrieved September 23, 2018 from www.sciencedaily.com/releases/2015/03/150302081147.htm

Licorice side effects and safety from WebMD

Allcock, E., & Cowdery, J. (2015). Hypertension induced by liquorice tea. BMJ Case Reports, 2015, bcr2015209926. http://doi.org/10.1136/bcr-2015-209926

Safe level of glycyrrhizic acid from WHO (World Health Organization)

Questions & Answers

    © 2012 Linda Crampton

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      • AliciaC profile imageAUTHOR

        Linda Crampton 

        15 months ago from British Columbia, Canada

        Hi, Kathy. Yes, licorice candy can certainly be a problem for the teeth. Licorice root is better, but it does need to be used with care. Briefly chewing a small piece of the root might be helpful, but I don't think that chewing it for a long time would be a good idea because it would give a lot of time for potentially harmful substances to be released from the root and absorbed into the body. Even chewing a small amount of the root could be dangerous because we don't know the concentration of the chemicals that we're absorbing.

      • profile image

        Kathy Kiesow 

        15 months ago

        Why not in the mea time, chew a portion of licorice root, then swish it in the mouth for 10 minutes or longer, and maybe even help it with coconut oil for oil pulling..I had no idea about the oral benefits of licorice, and I love licorice.But rarely eat the candy because of sugar.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        19 months ago from British Columbia, Canada

        Thanks for the comment and for sharing the information, Patty. Your friend's experience is definitely something to keep in mind.

      • Patty Inglish, MS profile image

        Patty Inglish MS 

        19 months ago from USA. Member of Asgardia, the first space nation, since October 2016

        This is a very interesting article. A friend in her 30s used to drink a cup of licorice root tea a few times a week. One day, she drank a quart of licorice root iced tea and had a full anaphylactic , allergic reaction. Went to the ER and was fine, but she was surprised.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        19 months ago from British Columbia, Canada

        Tom, since you are taking a blood pressure medication, I think it's very important that you talk to your doctor and perhaps your dentist as well before drinking a tea made from licorice root or using a licorice mouthwash.

      • profile image

        Tom 

        19 months ago

        Recently bought one pound of licorice root. Ground up two roots to use in tea. Have moderate BP and taking BP med. Don't believe it is crucial. Never had licorice candy made with real licorice. Don't plan to use it daily, however, considering making a wash to run in my water pick. Any thoughts?

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        3 years ago from British Columbia, Canada

        Thank you for the comment, Roberta. Congratulations on having your own teeth! I hope your friend is helped.

      • profile image

        roberta 

        3 years ago

        as one who has her own teeth at 77 i am inquiring for a person who has a qite severe problems with teeth and gums has no dental insurance per haps this ariticle can help prevent more damage with her doctors permission very well written

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        4 years ago from British Columbia, Canada

        Thank you very much for sharing your experience, Quila!

      • profile image

        Quila 

        4 years ago

        I love liquorice root and have been chewing it on and off for as long as I can remember. I don't know much about the chemicals it contains, but the stringy texture (once chewed) seems to make a great tasting toothbrush. Of course, it's also a pretty good laxative - whether you need one or not - so, whilst I've no idea how much is safe, I would definitely say no more than one stick a day ;-)

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        4 years ago from British Columbia, Canada

        Hi, anar. I've never seen any scientific reports about licorice root being an effective smoking cessation aid. It sounds risky to me because of the high chance of ingesting too much licorice. As you say, the danger of eating or sucking licorice root varies, depending on the size of the root, its chemical content and the frequency of use. There's a big chance of developing problems if multiple sticks are used each day, though, or even if one stick is used if it's big enough. Your doctor would probably be the best person to consult. I wish you luck in your quest to stop smoking.

      • profile image

        anar 

        4 years ago

        Have you come across any data about how much licorice is ingested by chewing on the root itself and swallowing the juices? Licorice root is often recommended as a smoking cessation aid, but it's not very clear how many sticks are considered safe to consume in a day, week etc. Obviously it must vary incredibly, but I wish I could find a ballpark rule of thumb to follow.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thanks for the comment, Doodlehead. It is nice to know that licorice has some health benefits!

      • Doodlehead profile image

        Doodlehead 

        6 years ago from Northern California

        Love that stuff. So nice to know it is healthy. Interesting about the gum disease bacteria.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        I agree, Peggy - more research does need to be done. The potential benefits look very helpful, though! I would certainly use licorice toothpaste and mouthwash if they were shown to improve oral health. Thank you for the votes.

      • Peggy W profile image

        Peggy Woods 

        6 years ago from Houston, Texas

        How very interesting! I used to love those licorice strands of candy when I was a kid but even back then seldom ate much candy. I had no idea of the possible healthful and well as harmful effects of using licorice. It would seem that more research needs to be done. I like the idea of licorice mouthwash or toothpaste...especially if it would cut down on harmful bacteria in the mouth. Go researchers!!! Up, useful and interesting votes!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thanks, Prasetio. I appreciate your comment and rating!

      • prasetio30 profile image

        prasetio30 

        6 years ago from malang-indonesia

        Again, you make this hub very detail and I learn many things from you. Thanks for writing and share with us. Rate up!

        Prasetio

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, Nell. Thanks for commenting. Yes, licorice does need to be taken in moderation, but it does seem to have some benefits, and it's certainly tasty!

      • Nell Rose profile image

        Nell Rose 

        6 years ago from England

        Hi, I remember reading years ago that it was good for asthmatics, but there was a down side there too, great stuff if taken in moderation, but as you say you have to be careful, thanks for the info, great stuff! cheers nell

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thank you very much for the comment and vote, Tom. I like licorice too, which I enjoy in the form of licorice tea. It's delicious!

      • kashmir56 profile image

        Thomas Silvia 

        6 years ago from Massachusetts

        Hi Alicia, great well written and researched hub on the benefits of using licorice safely . I love black licorice! I found the information was very interesting and some of it i did not know.

        Awesome and vote up !!!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thank you, Maren Morgan. That's a good way of describing licorice - it is tricky! It seems to offer some great health benefits, but it's important not to eat too much of it.

      • Maren Morgan M-T profile image

        Maren Elizabeth Morgan 

        6 years ago from Pennsylvania

        Sounds like a tricky chemical. Great research!

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        I would love chocolate toothpaste, drbj! I hope that someone invents it!! I've used toothpaste containing licorice, but just a small amount of licorice was added to the toothpaste to improve its flavor, not to be antibacterial. Thanks for the comment.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thank you very much for the kind comment, b. Malin! Licorice is certainly an interesting plant and substance. I love the taste of licorice, and its possible health benefits are intriguing.

      • drbj profile image

        drbj and sherry 

        6 years ago from south Florida

        I'm looking forward to seeing licorice toothpaste and chewing gum on the market, Alicia. 'Twould almost be as stupendous as finding chocolate toothpaste containing antibacterial properties. Don't laugh. Stranger things have happened.

        Thanks for this edifying and interesting hub.

      • b. Malin profile image

        b. Malin 

        6 years ago

        I used to LOVE Licorice as a child and now to hear how Beneficial it can be, may get me to once again eat it as an Adult! Just imagine Licorice Toothpaste! Wonderful, useful, Hub Alicia, once again, a most Enjoyable and Enlightening read.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Hi, Eddy. Thanks for the comment. I hope that you have a good day too!

      • Eiddwen profile image

        Eiddwen 

        6 years ago from Wales

        A very well informed and useful hub.

        Thank you for sharing;

        Take care and enjoy the rest of your day;

        Eddy.

      • AliciaC profile imageAUTHOR

        Linda Crampton 

        6 years ago from British Columbia, Canada

        Thank you, CMHypno. I agree, it is very important to look at the side effects of any herbal remedy, and of other medications too.

      • CMHypno profile image

        CMHypno 

        6 years ago from Other Side of the Sun

        Interesting article on licorice Alicia, especially as you look at the possible downsides of using licorice as well as the benefit. I think with all natural and herbal remedies it is important for people to investigate any potential side effects as well as the benefits

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