Glycyrrhizin

Diglucuronide of glycyrrhetinic acid. S. Glycyrrhiza glabra(licorice shrub). Glycyrrhizin is 150 times sweeter than sucrose. The substance determines the flavor of licorice.

Glycyrrhetinic acid (glycyrrhetinic acid) has an anti-inflammatory effect and inhibits melanin formation. In a gel formulation, it showed sustained release behavior and high transdermal permeability. This formulation had a significant preventive effect on melasma induced by progesterone injection and UVB irradiation. The expression of the melanin-related proteins MITF/TYR/TRP1 and TRP2 is downregulated. Glycyrrhizic acid applications are suitable for the treatment of melasma (Xiao Y et al. 2024).

It is known that glycyrrhizin can increase blood pressure depending on the dose. In the case of "strong liquorice" (> 400 mg glycyrrhizin per 100 g), manufacturers must affix a warning on the packaging. The Federal Institute for Risk Assessment recommends that consumers should not consume more than 100 mg of glycyrrhizin per day.

In individual cases, glycyrrhizin can also trigger prinzmetal angina in healthy hearts. The blood pressure-increasing effect of glycyrrhizin (in liquorice) is based on the inhibition of the enzyme 11-beta-hydroxysteroid dehydrogenase 2, an enzyme that transforms cortisol to cortisone. Inhibition of the enzyme leads to an increase in cortisol, which acts like aldosterone in high concentrations. Blood volume and blood pressure increase. In addition, hypokalemia, hypernatremia and metabolic alkalosis may develop (so-called pseudo-conn syndrome).

The enzyme 11-beta-hydroxysteroid dehydrogenase 2 is also detectable in the wall of blood vessels and is involved here in the regulation of vessel diameter. Animal experiments have shown that inhibition of the enzyme causes vasoconstriction and possibly angina pectoris.

In individual cases, excessive consumption of licorice can trigger angioedema due to glycyrrhizin.

Licorice and pregnancy: A Finnish study concluded that consumption of more than 500 mg of glycyrrhizin/week during pregnancy leads to an increased risk of premature birth.

Another study reported cognitive impairment in newborns whose mothers had eaten more than 100 g of licorice per week during pregnancy. Apparently, these children also suffer from intelligence defects (Raikkönen K et l 2009). Furthermore, symptoms of attention deficit hyperactivity disorder (ADHD) were found.

1. Machalke K et al. (2015) Prinzmetal angina after licorice consumption. Dtsch Med Wochenschr 140:590-592.

2. Räikkönen K et al. (2009) Maternal licorice consumption and detrimental cognitive and psychiatric outcomes in children. Am J Epidemiol 170:1137-1146.
3. Xiao Y et al. (2024) Preparation of paeoniflorin-glycyrrhizic acid complex transethosome gel and its preventive and therapeutic effects on melasma. Eur J Pharm Sci 192:106664.