New findings suggest that chemicals in liquorice, used as a remedy for gastrointestinal disorders, could have an effect on testosterone levels.
New research, presented at the British Pharmaceutical Conference this week, follows previous studies that have suggested such an effect on men, although the results have proved controversial.
Reduced testosterone levels were reported in an Italian study in 1999, but US researchers were unable to replicate this finding in a study published in the Lancet two years later.
In the new research, a team from Iran, led by Dr Mahmoud Mosaddegh from the Traditional Medicine & Materia Medica Research Centre at Shaheed Beheshti University of Medical Sciences, in Tehran, investigated the effect of liquorice root extract in 20 healthy male volunteers. The group took 1.3g of dried extract (containing around 400-500mg glycyrrhizic acid) daily for 10 days. Blood samples were collected before the study and for 20 days to measure testosterone levels.
There was found to be a significant decrease in serum testosterone levels after 10 days' liquorice consumption.The effect on testosterone is believed to relate to interference of the active agent glycyrrhizic acid with 17-beta hydroxysteroid dehydrogenase, the enzyme thatcatalyses conversion of androstenedione to testosterone.
"More research is needed to assess the hormonaleffects of liquorice. Liquorice root extract is a popular treatment, traditionally used for treatment of gastrointestinal disorders, but until further data are available we would advise caution in use of the extract," said Dr Mosaddegh.
The liquorice plant recently gained attention as researchers in Germany reported positive effects of the plant's root on the SARS virus. Liquorice is also found in the controversial prostate health supplement PC SPES.