Licorice (Glycyrrhiza glabra) is a herb found in many dietary supplements marketed to boost energy and for colds and flus and digestive problems.
A study, published in September 2003, suggests that licorice may reduce levels of the hormone testosterone in men. After one week of treatment with licorice, testosterone levels decreased 26%.
At least one other study was not able to confirm this finding, but instead found decreased levels of another hormone, DHEA-s. More research is needed to understand the connection between testosterone and hormones in men.
Sources:
Armanini D, Bonanni G, Mattarello MJ, Fiore C, Sartorato P, Palermo M. Licorice consumption and serum testosterone in healthy man. Exp Clin Endocrinol Diabetes. (2003) 111.6: 341-3.
Sigurjonsdottir HA, Axelson M, Johannsson G, Manhem K, Nystrom E, Wallerstedt S. Liquorice in moderate doses does not affect sex steroid hormones of biological importance although the effect differs between the genders. Horm Res. (2006) 65.2: 106-10.
