Licorice and Home Blood Pressure

Out-of-office blood pressure is more strongly associated with cardiovascular risk than office blood pressure. Licorice is known to raise blood pressure, but no previous studies have measured the effects on home blood pressure. The aim of this study is to analyze the association between licorice intake and home blood pressure.

Healthy volunteers will be invited to participate in a randomized, non-blinded, cross-over study. Participants will be randomized to either of two groups with a 1:1 allocation ratio, stratified by sex. Intervention will be sweet licorice and control will be salty licorice. A run-in period of 1 week will be followed by a 2-week intervention/control, a 2-week washout period, another 2-week control/intervention period and again a 2-week washout period. Home blood pressure will be measured continuously, and blood samples (including potassium and aldosterone) will be collected every two weeks. Analyses will be made comparing baseline characteristics of the two groups, intervention/control and washout period results of the two groups to look for potential carry-over effects, and finally comparing intervention and washout period results respectively to the baseline data to look for the effects of licorice.

This arm will be divided into the following periods: Run-in period: 7 days without any licorice intake Intervention period: 14 days with sweet licorice intake First wash-out period: 14 days without any licorice intake Control period: 14 days with salty licorice intake Second wash-out period: 14 days without any licorice intake.

This arm will be divided into the following periods: Run-in period: 7 days without any licorice intake Control period: 14 days with salty licorice intake First wash-out period: 14 days without any licorice intake Intervention period: 14 days with sweet licorice intake Second wash-out period: 14 days without any licorice intake.

Ecologic, vegan and gluten free, low-sodium sweet licorice pastilles made from Glycyrrhiza glabra, with a manufacturer specified content of 4% sugars, 2% glycyrrhizin and 0.03% salt, will be used as intervention. The exact glycyrrhizin content will be determined before the study begins, and participants will be instructed to consume a daily licorice dose that is equivalent to 100 mg of glycyrrhizin.

A vegan and gluten free salty licorice without glycyrrhizin, flavored with ammonium chloride, with a manufacturer specified content of 0% sugars and 0.05% salt, will be used as control. The amount of salty licorice will be the same as for sweet licorice, and thus determined after the glycyrrhizin content analysis of the sweet licorice.

Inclusion Criteria: Age 18 to 30 years Exclusion Criteria: known hypertension, cardiovascular disease, kidney disease, liver disease, hormonal disease, peanut allergy, eating disorder or headache disease (including tension headache and migraine) known alcohol abuse or drug abuse (including cannabis and anabolic steroids) treatment with hormonal drugs (including oral contraceptives known intolerance to licorice intake

After publication in a peer-reviewed journal and for the period of time for which local archive regulations stipulate.

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