ADHD News & Research

New Study: Prenatal Exposure to Licorice May Be Linked to ADHD

An unexpected link between licorice – often recommended for its health benefits – and ADHD in children adds this candy to the list of foods to avoid during pregnancy.

February 7, 2017

Licorice consumption during pregnancy may be associated with harm for the developing offspring.”

This comes from the team of Finnish researchers behind a recent study, published in the American Journal of Epidemiology, that analyzed 378 preteens born in Helsinki, Finland, in 1998. The researchers evaluated the impact of glycyrrhizin – the active ingredient in licorice – on psychiatric and developmental issues during childhood using the Pubertal Developmental Scale, neuropsychological tests, and the Child Behavior Checklist.

The results showed that children born to mothers with a high glycyrrhizin intake (more than 500 milligrams) performed poorly on intelligence and memory tests, and were more likely to exhibit symptoms of ADHD when compared to children born to mothers with a low glycyrrhizin intake (less than 249 milligrams). Additionally, girls were more likely to experience early puberty if their mothers ate the equivalent of 250 grams of licorice candy during pregnancy.

A previous study, by the same first author, found that glycyrrhizin affected fetal brain development by inhibiting the enzyme that deactivates cortisol. By age 8, children of mothers who consumed large amounts of licorice were more likely to have attention, rule-breaking, and aggressive behavior problems, along with poorer memory.

In Finland, licorice candy is a common treat. In the United States, the candy is less popular, but people may consume more glycyrrhizin than they realize. It is commonly used as a low-calorie sweetener – 50 to 200 times sweeter than sugar – and flavoring agent in products including chewing gum, herbal tea, alcoholic and nonalcoholic beverages, and over-the-counter or herbal remedies. Daily intake could be as little as 1.6mg or as great as 215.2mg without consuming candy.

This new research suggests that expectant mothers should exercise caution with products containing glycyrrhizin, as it may have long-term developmental effects. Pregnant mothers should discuss this research and prenatal dietary safety with their doctors.

Journal Reference:

Katri Räikkönen, Silja Martikainen, Anu-Katriina Pesonen, Jari Lahti, Kati Heinonen, Riikka Pyhälä, Marius Lahti, Soile Tuovinen, Karoliina Wehkalampi, Sara Sammallahti, Liisa Kuula, Sture Andersson, Johan G. Eriksson, Alfredo Ortega-Alonso, Rebecca M. Reynolds, Timo E. Strandberg, Jonathan R. Seckl, Eero Kajantie; Maternal Licorice Consumption During Pregnancy and Pubertal, Cognitive, and Psychiatric Outcomes in Children. Am J Epidemiol 2017 1-12. doi: 10.1093/aje/kww172