Liquorice and its natural sweetener, glycyrrhizin, can have long-term harmful effects on the development of the foetus, according to a Finnish study.
The study supports food recommendations for families with children in that women should avoid consuming large amounts of liquorice during pregnancy, said the researchers behind the work.
“Licorice consumption during pregnancy may be associated with harm”
They added that it had long been known that glycyrrhizin caused higher blood pressure and shorter pregnancies in humans, but such long-lasting effects on the foetus had not been proven before. They also highlighted that the limit for safe consumption was not known.
In the study, teenagers that had been exposed to large amounts of liquorice in the womb performed less well than others in cognitive reasoning tests carried out by a psychologist.
The difference was equivalent to approximately seven IQ points. Those exposed to liquorice also performed less well in tasks measuring memory capacity, said the researchers.
In addition, according to parental estimates, they had more attention deficit hyperactivity disorder-type problems than others. With girls, puberty had started earlier and advanced further.
The study, published in the American Journal of Epidemiology, involved 378 children of about 13-years-old whose mothers had consumed “large amounts” or “little/no” liquorice during pregnancy.
A large amount was defined as over 500mg and little/no as less than 249mg glycyrrhizin per week.
The cut-offs were not based on health effects, noted the researchers, who said that 500mg glycyrrhizin corresponded on average to 250g liquorice.
Researchers suggest that pregnant women and women planning pregnancy should be informed of the harmful effects that products containing glycyrrhizin – such as liquorice and salty liquorice – may have on the foetus.
“Licorice consumption during pregnancy may be associated with harm for the developing offspring,” said the study authors led by Professor Katri Räikkönen from the University of Helsinki.
However, the researchers acknowledged that things should be kept in proportion. Glycyrrhizin is one of many factors that affect the development of a foetus, they said, adding that it was impossible to say whether it was glycyrrhizin expressly that affected the development of a certain individual.
As a result of animal experiments, they said the biological mechanism of the effects of liquorice is well known. Glycyrrhizin intensifies the effects of stress hormone cortisol by inhibiting the enzyme that inactivates cortisol. Cortisol is essential to foetal development but is detrimental in large amounts.