Voluntary liquorice ingestion increases blood pressure via increased volume load, elevated peripheral arterial resistance, and decreased aortic compliance

Abstract

We investigated the haemodynamic effects of two-week liquorice exposure (glycyrrhizin dose 290–370 mg/day) in 22 healthy volunteers during orthostatic challenge. Haemodynamics were recorded during passive 10-minute head-up tilt using radial pulse wave analysis, whole-body impedance cardiography, and spectral analysis of heart rate variability. Thirty age-matched healthy subjects served as controls. Liquorice ingestion elevated radial systolic (p < 0.001) and diastolic (p = 0.018) blood pressure and systemic vascular resistance (p = 0.037). During orthostatic challenge, heart rate increased less after the liquorice versus control diet (p = 0.003) and low frequency power of heart rate variability decreased within the liquorice group (p = 0.034). Liquorice intake increased central pulse pressure (p < 0.001) and augmentation index (p = 0.002) supine and upright, but in the upright position the elevation of augmentation index was accentuated (p = 0.007). Liquorice diet also increased extracellular fluid volume (p = 0.024) and aortic to popliteal pulse wave velocity (p = 0.027), and aortic characteristic impedance in the upright position (p = 0.002). To conclude, in addition to increased extracellular fluid volume and large arterial stiffness, two weeks of liquorice ingestion elevated systemic vascular resistance and augmentation index. Measurements performed at rest may underestimate the haemodynamic effects of liquorice ingestion, as enhanced central wave reflection and reduced chronotropic response were especially observed in the upright position.

Liquorice ingestion attenuates vasodilatation via exogenous nitric oxide donor but not via β2-adrenoceptor stimulation

“…Previously, we found that liquorice intake for two weeks increased BP via volume expansion, elevated peripheral arterial resistance and increased large arterial stiffness [17]. We also observed reduced chronotropic response and enhanced central wave reflection in the upright posture after liquorice exposure [17].…”

“…The study protocol (in Finnish) with an English summary have been published [18], and the CONSORT checklist is presented as supporting information (S1 CONSORT checklist). The recruitment and characteristics of the subjects in the liquorice group and the study design were reported elsewhere [17,18]. The present results originate from the same liquorice intervention from which we published results concerning liquorice-induced changes in haemodynamics in the supine position [18] and during orthostatic challenge [17].…”

“…In the present study, the focus was on the mechanisms of vasodilatation induced by exogenous NO (nitroglycerin) and β 2 -adrenoceptor stimulation (salbutamol) after 2 weeks of liquorice intake. The intervention group was the same as in earlier reports [17,18], while all findings concerning NO and β 2 -adrenoceptor-induced vasodilatation are novel, and the reference group is new. The participants were recruited via announcements distributed at the Tampere University, Tampere University Hospital, and occupational health care units, and through notices in a local newspaper, and Varala Sports Institute.…”

“…Previously, we found that liquorice intake for two weeks increased BP via volume expansion, elevated peripheral arterial resistance and increased large arterial stiffness [17]. We also observed reduced chronotropic response and enhanced central wave reflection in the upright posture after liquorice exposure [17]. To examine the mechanisms underlying the elevation of systemic arterial resistance, here we investigated possible alterations in vasodilatory responses induced by exogenous NO donor and β 2 -adrenoceptor agonist after liquorice exposure in supine and upright positions.…”

Expert panel consensus recommendations for ambulatory blood pressure monitoring in Asia: The HOPE Asia Network

“…Specific agents such as non‐steroidal anti‐inflammatory drugs (NSAIDs) and Kanzo [liquorice] increase the circulating volume, resulting in a non‐dipping pattern and nocturnal hypertension …”