Letter


British Dental Journal 207, 519 (2009)
Published online: 12 December 2009 | doi:10.1038/sj.bdj.2009.1090

Liquorice alert

K. Takami1, L. Z. G. Touyz1 & R. M. Touyz1

Send your letters to the Editor, British Dental Journal, 64 Wimpole Street, London W1G 8YS e-mail: bdj@bda.org

Priority will be given to letters less than 500 words long.

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Sir, we bring to your attention concerns regarding possible adverse clinical effects of an innovative anti-caries lollipop containing a liquorice derivative.

Much fanfare has heralded the introduction of a new cavity-fighting lollipop containing a liquorice root extract that inhibits the growth of Streptococcus, important in initiating dental caries.1, 2 Should global consumption of this liquorice-flavoured candy be adopted the prevalence of dental decay may be reduced. However, excessive lollipop use is cautioned because over-consumption of liquorice has potential clinical risks. Liquorice is a ubiquitously employed food flavourant that also possesses therapeutic properties.3 As such its commercial use is at an all-time high. The major active ingredient of liquorice, glycyrrhizin, is 100-200 times sweeter than processed sugar. In addition to its flavour-enhancing qualities, glycyrrhizin exerts many pharmacological actions, such as its anti-cariogenic effects.

Excessive intake of glycyrrhizin is associated with adverse side effects including increased blood pressure, hypernatraemia and hypokalaemia. Glycyrrhizin blocks the activity of the enzyme, 11 beta-hydroxysteroid dehydrogenase type 2, that converts cortisol to inactive cortisone. Cortisol, in turn, binds to mineralocorticoid receptors (MR), promoting sodium reabsorption, potassium excretion and hypertension, a clinical triad characteristic of liquorice-induced pseudoaldosteronism,4 which is becoming a more frequent phenomenon with increased use of liquorice as flavourants.

Dosage needs consideration when assessing glycyrrhizin-related risks. The Joint FAO/WHO Expert Committee on Food Additives and the European Community's Scientific Committee on Food recommend a maximum of 100 mg/day. Glycyrrhizin consumption levels in USA are 0.03-3.6 mg/kg/d and at its upper limit, would exceed the above recommendations in individuals over 30 kg. Allowable glycyrrhizin content varies amongst foods: lowest in baked goods, highest in hard candy. Many published cases of pseudoaldosteronism involve excessive consumption of liquorice/glycyrrhizin. One could argue that these levels are higher than could be achieved through even heavy consumption of the anti-caries lollipops. Although the glycyrrhizin concentration in these lollipops is not available and it is reasonable to assume that each lollipop contains low levels of glycyrrhizin, cumulative effects of multiple lollipops and other sources of ingested glycyrrhizin (tobacco, herbal medicines, candy), may raise levels beyond the recommended limit.

Marketing of these lollipops is largely targeting children and the elderly, two sub-populations particularly susceptible to the mineralocorticoid actions of liquorice. For instance, with the rising incidence of childhood obesity and accompanying health complications including diabetes and hypertension, excessive liquorice intake in children may compound pre-existing health risks.

We feel that cavity-fighting lollipops are innovative anti-caries products, appealing to the public and economically attractive to the health care system. The fact that liquorice and its derivatives are exempt from FDA regulation may inadvertently project a false sense that liquorice ingestion is safe at even high levels. Here, we raise concerns regarding overconsumption of liquorice-containing food and medicinal products. We alert the dental community of the potential clinical risks of excessive or prolonged use of these lollipops and the importance of educating patients on complying with specified doses for the lollipops (ie two per day, for up to ten days).

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References

  1. Belt D. Licorice root lollipop shows sweet promise in reducing tooth decay. J Calif Dent Assoc 2008; 36: 243-249.
  2. Segal R, Pisanty S, Wormser R, Azaz E, Sela M N. Anticariogenic activity of licorice and glycyrrhizine I: Inhibition of in vitro plaque formation by Streptococcus mutans. J Pharm Sci 1985; 74: 79–81. | Article | PubMed | ChemPort |
  3. Isbrucker R A, Burdock G A. Risk and safety assessment on the consumption of Licorice root (Glycyrrhiza sp.), its extract and powder as a food ingredient, with emphasis on the pharmacology and toxicology of glycyrrhizin. Regul Toxicol Pharmacol 2006; 46: 167–192. | Article | PubMed | ChemPort |
  4. Sontia B, Mooney J, Gaudet L, Touyz R M. Pseudohyperaldosteronism, liquorice, and hypertension. J Clin Hypertens (Greenwich) 2008; 10: 153–157. | Article | PubMed
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