Licorice inhibits an enzyme responsible for the conversion of cortisol to cortisone, which has been shown to increase the cortisol-to-cortisone ratio when the dosage of glycyrrhetinic acid is more than 500 mg per day.[1][2][3][4][5] Elevations in cortisol can lead to high blood pressure and metabolic alkalosis, mimicking a condition known as hyperaldosteronism.[6][2]
Increases in parathyroid hormone levels have also been observed in women who took licorice (3.5 grams per day over 2 months).[7] Licorice can inhibit enzymes leading to a decrease in DHEA, but this effect may be more pronounced in men.[5]
Licorice also appears to inhibit testosterone production through enzymatic inhibition, thus lowering testosterone levels.[8][9] This appears to be a dose-dependent response. Licorice extract taken at 5–7 grams daily (containing 500 mg of glycyrrhizic acid) resulted in testosterone reductions in men, but the levels returned to normal when they stopped. Lower dosages do not appear to significantly affect testosterone levels.[8][10][11][12][5]
Phytoestrogens are also found in licorice. Glabrene and liquiritigenin, for example, may activate some estrogen receptors, while glabridin seems to selectively modulate them.[8][13][14][15][16][17]