Abstract
Background:
Licorice, through the effects of glycyrrhizic acid (GA), raises blood pressure (BP). The World Health Organization has suggested that 100 mg of GA per day would be unlikely to cause adverse effects, but of 13 previously published studies none have been randomized and controlled, and independently quantified the GA content.
Objective:
Our aim was to analyze the effects on home BP of a daily licorice intake containing 100 mg of GA.
Methods:
Healthy volunteers were randomized to start with either licorice or a control product in a non-blinded, 2x2 cross-over study. Home BP was measured daily, and blood samples were collected at the end of each 2-week period.
Results:
There were 28 participants and no dropouts. The median age was 24.0 (interquartile range 22.8-27.0) years. During the licorice vs control period, the systolic home BP increased, mean (95% confidence interval [CI]) difference 3.1 (0.8-5.4) vs -0.3 (-1.8 to 1.3) mmHg, P = .018, and renin and aldosterone were suppressed, mean (95% CI) change -30.0 (-56.7 to -3.3) vs 15.8 (-12.8 to 44.4) %, P = .003, and -45.1 (-61.5 to -28.7) vs 8.2 (-14.7 to 31.1) %, P <.001, respectively. In the quartile of participants with the most pronounced suppression of renin and aldosterone, N-terminal prohormone of brain natriuretic peptide (NT-ProBNP) increased during the licorice vs control period, mean (95% CI) change 204.1 (-11.6 to 419.7) vs 72.4 (-52.2 to 197.1) %, P = .016.
Conclusion:
We found licorice to be more potent than previously known, with significant increases in BP, after a daily intake of only 100 mg of GA. Thus, the safe limit of intake of this substance might need to be reconsidered.
Clinical trial registry number:
NCT05661721, https://clinicaltrials.gov/study/NCT05661721.
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