Reduction of Serum Testosterone in Men by Licorice

Abstract

Extracts of licorice root are widely used in many countries as flavoring agents, breath fresheners, or candy. The active component of licorice is glycyrrhizic acid, which is hydrolyzed in vivo to glycyrrhetinic acid. The well-known mineralocorticoid-like effect of licorice results from the inhibition of 11β-hydroxysteroid dehydrogenase, the enzyme that catalyzes the conversion of cortisol to cortisone, thereby minimizing the binding of cortisol to mineralocorticoid receptors.¹ Licorice may also directly activate mineralocorticoid receptors.² In vitro, licorice can block 17β-hydroxysteroid dehydrogenase, which catalyzes the conversion of androstenedione to testosterone.³