Daily liquorice consumption for two weeks increases augmentation index and central systolic and diastolic blood pressure

PLoS One. 2014 Aug 25;9(8):e105607. doi: 10.1371/journal.pone.0105607. eCollection 2014.


Background: Liquorice ingestion often elevates blood pressure, but the detailed haemodynamic alterations are unknown. We studied haemodynamic changes induced by liquorice consumption in 20 subjects versus 30 controls with average blood pressures of 120/68 and 116/64 mmHg, respectively.

Methods: Haemodynamic variables were measured in supine position before and after two weeks of liquorice consumption (daily glycyrrhizin dose 290-370 mg) with tonometric recording of radial blood pressure, pulse wave analysis, and whole-body impedance cardiography. Thirty age-matched healthy subjects maintaining their normal diet were studied as controls.

Results: Two weeks of liquorice ingestion elevated peripheral and central systolic and diastolic blood pressure (by 7/4 and 8/4 mmHg, 95% confidence intervals [CI] 2-11/1-8 and 3-13/1-8, respectively, P<0.05), and increased extracellular volume by 0.5 litres (P<0.05 versus controls). Also augmentation index adjusted to heart rate 75/min (from 7% to 11%, 95% CI for change 0.3-7.5, P<0.05) and aortic pulse pressure (by 4 mmHg, 95% CI 1-7, P<0.05) were elevated indicating increased wave reflection from the periphery. In contrast, peripheral (-3/-0.3 mmHg) and central blood pressure (-2/-0.5 mmHg), aortic pulse pressure (-1 mmHg), and augmentation index adjusted to heart rate 75/min (from 9% to 7%) decreased numerically but not statistically significantly without changes in extracellular volume in the control group. Heart rate, systemic vascular resistance, cardiac output, and pulse wave velocity did not differ between the groups.

Conclusions: Two weeks of daily liquorice consumption increased extracellular volume, amplified pressure wave reflection from the periphery, and elevated central systolic and diastolic blood pressure.

Trial registration: EU Clinical Trials Register EudraCT 2006-002065-39 ClinicalTrials.gov NCT01742702.

Publication types

  • Controlled Clinical Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Pressure / physiology*
  • Candy*
  • Female
  • Glycyrrhiza*
  • Heart Rate / physiology*
  • Hemodynamics / physiology
  • Humans
  • Male
  • Pulse Wave Analysis

Associated data

  • ClinicalTrials.gov/NCT01742702

Grant support

Competitive State Research Financing of the Expert Responsibility Area of Tampere University Hospital, the Finnish Foundation for Cardiovascular Research, the Sigrid Jusélius Foundation, the Paavo Nurmi Foundation, the Pirkanmaa Regional Fund of the Finnish Cultural Foundation, the Tampere Tuberculosis Foundation, and Astra Zeneca Plc. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.