Sex Hormones

Testosterone Whether licorice consumption affects testosterone levels is still unknown, as conflicting results have been obtained from clinical studies. Armanini et al have conducted a series of trials investigating the effects of licorice on testosterone levels in males with mixed results (Armanini et al 1999, 2003a).

One study showed that licorice (7 g/day equivalent to 0.5 g GA) was able to reversibly reduce testosterone levels within 7 days, by inhibiting 17,20-lyase (involved in the conversion of 17-hydroxyprogesterone to androstenedione) and 17-beta-hydroxysteroid dehydrogenase (involved in the conversion of androstenedione to testosterone) (Armanini et al 1999). Another study twice attempted to replicate these results, but was unable to detect an effect on testosterone levels in either study; the authors suggest that inappropriate use of statistical tests in the first study may explain the varying results (Josephs et al 2001).

More clinically promising are the results from a small trial of nine healthy women (22-26 years) in the luteal phase of their menstrual cycle. The women received 3.5 g licorice (containing 7.6% w/w of GL) daily for two cycles. Total serum testosterone decreased from 27.8 (±8.2) to 19.0 (±9.4) ng/dL in the first month and to 17(±6.4) ng/dL in the second month of therapy (Armanini et al 2004). Further larger scale trials are required to confirm these effects in women with conditions of elevated testosterone such as hirsutism and PCOS.

Oestrogen Licorice contains isoflavones, including licochalcone-A, which are also known as 'phyto-oestrogens' because they act as partial oestrogen agonists in the body (Setchell & Cassidy 1999). Additionally, in vitro studies suggest that stimulation of aromatase activity promotes oestradiol synthesis (Takeuchi et al 1991).

Liquiritigenin and isoliquiritigenin have displayed oestrogenic affinity to sex hormone-binding globulin and oestrogen receptors in vitro (Hillerns et al 2005) and

g la b rid in and glabrene have both demonstrated oestrogen-like activities similar to oestradiol-17(beta) in animal studies (Somjen et al 2004a).

In vitro studies also suggest the potential for glabridin to enhance osteoblast function (Choi 2005). As a result glabridin has been proposed as a possible therapeutic aid in the prevention of osteoporosis and inflammatory bone diseases (Choi 2005), as well as cardiovascular diseases and bone disorders, in postmenopausal women (Somjen et al 2004a, b).

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