A sweet masquerade: liquorice stools
Timothy Bemand, Mandy Kaur, Catherine Mannering, Ryan Cater, A/Prof Joseph Suttie
Background
Liquorice, whilst used for centuries as a traditional medicine in a range of cultures, is associated with a range of adverse effects. There is a well described association with the syndrome of apparent mineralocorticoid excess (SAME) due to the active component of liquorice (glycyrrhizin) causing inhibition of 11-beta hydroxysteroid dehydrogenase and subsequent increase in serum cortisol (Omar et al., 2012). This can lead to severe hypertension and hypokalaemia. Previous case reports of liquorice toxicity include complications of severe hypertension, including hypertensive emergency (Falet, Elkrief, & Green, 2019) and posterior reversible encephalopathy syndrome (O'Connell, Kinsella, McMahon, Holian, & O'Riordan, 2016). Other case reports have described hypokalaemia with subsequent myopathy and arrythmias (Panduranga & Al-Rawahi, 2013), rhabdomyolysis (Liew & Lee, 2017), peripheral oedema and heart failure. In addition, due to inhibition of CYP-450 enzymes liquorice can cause a number of drug interactions including notably with warfarin and digoxin (Omar et al., 2012).
However, despite being a described phenomena, and experienced personally by one of the authors after consuming 200g of liquorice, the authors are only aware of two case reports describing liquorice causing black stools (Liu, Srivatsa, & Kaul, 2010; Picca, 1979), and there is no published data about the expected doses of confectionary liquorice required to cause apparent melaena (“pseudo-malanea”).
Aims
To explore the average quantity of liquorice needed to be consumed that leads to black discoloration of stools mimicking melaena.
Methods
In the long and noble tradition of self-experimentation in medicine, the authors undertook a ramped dose toxicology study consuming increasing quantities of liquorice and observing for change in stool colour that could be confused as melaena. All authors participating were healthy and well, with no history of gastrointestinal bleeding, ordinarily normal bowel motions, and experience in healthcare such that they could recognise stool that appeared to mimic melaena. Exclusion criteria included pre-existing hypertension, use of oral iron supplementation, use of medications metabolised by CYP-450 pathway.
Generic Woolworths Liquorice Twists were used containing 1% liquorice root extract. Doses used were 100g, 150g, 200g, 250g, 300g and 350g. After 72 hours post consumption of one dose, if no change in stool colour was observed the next higher dose was taken. If black stool discoloration was observed, the next dosage was taken after stools returned to normal colour. Primary outcome was the dose of liquorice required for 50% of participants to observe stool change consistent with melaena.
Results
Nine individuals were invited to participate and share authorship, only five expressed interest.
Four of the five authors commenced the study, and three completed the protocol to consume 350g liquorice; one author consumed a maximum of 150g liquorice.
No participants observed any changes in their stools over the study period that would be confused as melaena, therefore the primary outcome of dose required for 50% of participants to experience pseudo-malaena could not be determined.
There were no reported adverse events or deaths.
Discussion:
It was surprising and unexpected that despite large doses of black confectionary liquorice intake, there were no observed changes in stool colour. It is likely that variations in types and relative concentrations of additives and liquorice ingredients may mean that a different result is obtained with repeat testing using a different brand.
Our difficulties in finding coauthors willing to consume moderate to large quantities of liquorice highlights the divisive nature of liquorice as a confectionary item..
References
- Falet, J. P., Elkrief, A., & Green, L. (2019). Hypertensive emergency induced by licorice tea. CMAJ Canadian Medical Association Journal, 191(21), E581-E583. doi:10.1503/cmaj.180550
- Liew, Z. H., & Lee, K. G. (2017). Liquorice-Induced Severe Hypokalaemic Rhabdomyolysis with Acute Kidney Injury. Annals of the Academy of Medicine, Singapore, 46(9), 354-355.
- Liu, J. F., Srivatsa, A., & Kaul, V. (2010). Black licorice ingestion: yet another confounding agent in patients with melena. World Journal of Gastrointestinal Surgery, 2(1), 30.
- O'Connell, K., Kinsella, J., McMahon, C., Holian, J., & O'Riordan, S. (2016). Posterior reversible encephalopathy syndrome (PRES) associated with liquorice consumption. Irish Journal of Medical Science, 185(4), 945-947.
- Omar, H. R., Komarova, I., El-Ghonemi, M., Fathy, A., Rashad, R., Abdelmalak, H. D., . . . Camporesi, E. M. (2012). Licorice abuse: time to send a warning message. Therapeutic advances in endocrinology and metabolism, 3(4), 125-138. doi:10.1177/2042018812454322
- Panduranga, P., & Al-Rawahi, N. (2013). Licorice-induced severe hypokalemia with recurrent torsade de pointes. Annals of Noninvasive Electrocardiology, 18(6), 593-596. doi:10.1111/anec.12076
- Picca, S. (1979). Licorice stool. The New England journal of medicine, 300(22), 1283-1283.