Licorice — a sweet root that can raise blood pressure?

Aim of the study: To investigate the effects of consuming licorice functional ingredients on blood pressure, explore their potential mechanisms of action, and provide safety information for personalized nutritional interventions in special populations and for the use of licorice-derived functional foods.

Results: Eight RCTs (541 participants) were included in the meta-analysis, which found that interventions containing glycyrrhizic acid (GA) as the main component increased systolic blood pressure (SBP) and diastolic blood pressure (DBP) (SBP: WMD [95% CI] = 3.48 [2.74, 4.21], p < 0.001; DBP: WMD [95% CI] = 1.27 [0.76, 1.78], p < 0.001). However, interventions mainly containing licorice flavonoids (LF) had no significant effect on SBP or DBP (SBP: WMD [95% CI] = 0.58 [-1.15, 2.31], p = 0.511; DBP: WMD [95% CI] = 0.17 [-1.53, 1.88], p = 0.843). Three machine-learning algorithms identified five biomarkers associated with hypertension: calmodulin 3 (CALM3), cluster of differentiation 9 (CD9), growth factor independence 1B transcriptional repressor (GFI1B), myosin light chain kinase (MYLK), and Ras suppressor-1 (RSU1). After biomarkers with lower validity and reliability were removed, GFI1B, MYLK, and RSU1 were selected for further analysis.

Aim of the study: There have been numerous case reports of severe adverse events, including deaths, following chronic licorice ingestion. The aim of the present study was to evaluate the effect of chronic licorice ingestion on blood pressure, plasma potassium, plasma renin activity, and plasma aldosterone.

Results: Plasma potassium (-0.33 mmol l-1, 95% CI -0.42 to 0.23), plasma renin activity (-0.82 ngml-1 per hour, 95% CI -1.27 to -0.37), and plasma aldosterone (-173.24 pmol l-1, 95% CI -231.65 to -114.83) were all significantly decreased. A significant correlation was found between the daily dose of glycyrrhizic acid and systolic blood pressure (r2=0.55) and diastolic blood pressure (r2=0.65), but not with the other outcome measures. Thus, chronic licorice ingestion is associated with an increase in blood pressure and a decrease in plasma potassium, even at modest doses. This is particularly relevant for people with existing cardiovascular disease.

Aim of the study: Licorice raises blood pressure (BP) through the effects of glycyrrhizic acid (GA). The World Health Organization has suggested that 100 mg GA/d is unlikely to cause adverse effects, but none of 13 previously published studies were randomized and controlled or independently quantified the GA content. Our aim was to analyze the effects on home BP of daily licorice intake containing 100 mg GA.

Results: There were 28 participants and no dropouts. The median age was 24.0 y (interquartile range 22.8-27.0 y). During the licorice intake period compared with the control period, home systolic BP increased [mean difference: 3.1 mm Hg (95% confidence interval [CI]: 0.8, 5.4 mm Hg) compared with -0.3 mm Hg (95% CI: -1.8, 1.3 mm Hg); P = 0.018], and renin and aldosterone were suppressed [mean change: -30.0% (95% CI: -56.7%, -3.3%) compared with 15.8% (95% CI: -12.8%, 44.4%); P = 0.003; and -45.1% (95% CI: -61.5%, -28.7%) compared with 8.2% (95% CI: -14.7%, 31.1%); P <0.001, respectively]. In the quartile of participants with the strongest suppression of renin and aldosterone, N-terminal prohormone of brain natriuretic peptide concentration increased during the licorice period compared with the control period [mean change: 204.1% (95% CI: -11.6%, 419.7%) compared with 72.4% (95% CI: -52.2%, 197.1%); P = 0.016].