Damiana

Turnera diffusa Willd. ex Schult.

Synonyms:

T. aphrodisiaca Ward; T. diffusa var. aphrodisiaca (Ward) Urb.; T. diffusa var. diffusa; and others

Indications/uses: Damiana is used to relieve fatigue and nervous exhaustion and has been included in formulations with other medicinal plants to treat male dysfunction and impotence. It is regarded as a tonic and sexual stimulant. Traditionally, damiana has a number of other uses, and is taken to alleviate menopausal symptoms and for its reputed digestive, diuretic, antimalarial, anti-ulcer and hypoglycaemic properties. It is found mainly in THR products in combination with other medicinal plants (including cola and saw palmetto). Damiana is listed as a flavour ingredient by the Council of Europe and is permitted to be added in small quantities in foodstuffs.

Evidence: There is limited pharmacological evidence to support the traditional uses of damiana leaf. Its reputed aphrodisiac properties have not been fully substantiated in humans, although studies have shown that it improves sexual function in male rats. There is some evidence that preparations containing damiana may help induce weight loss when taken regularly for 45 days.

Safety: Safety and toxicological data are limited for damiana leaf preparations, although results from an in vivo study in mice indicate that it is relatively non-toxic, having an L_D50 > 5,000 mg/kg with a single i.p. dose. However, due to the reported presence of toxic cyanogenic glycosides and the constituent arbutin, long-term use or high doses are not recommended. No information on the safety of damiana during pregnancy and lactation is available; but doses in excess of those found in food should be avoided.

Main chemical compounds:

Chemical studies on damiana leaf are limited. Damiana leaf has been reported to contain traces of cyanogenic glycosides (tetraphyllin B) and the phenolic glycoside arbutin, an essential oil (0.2–0.9%) containing α- and β-pinene, thymol, α-copaene, δ-cadinene calamenene and others, flavonoid glycosides and traces of β-sitosterol (EMEA 1999; Pharmaceutical Press Editorial Team 2013; Zhao et al. 2007).

Clinical evidence:

Clinical data are limited. One small double-blind placebo-controlled study of 34 women given a nutritional supplement (‘Argin Max’) containing damiana extract for 4 weeks, showed improvement in sexual desire, reduction in vaginal dryness, increase in sexual intercourse and orgasm and improvement in clitoral sensation (Kumar et al. 2005). Small clinical studies have shown significant weight loss effects with damiana extracts given for 45 days (Kumar et al. 2005), as did a double-blind placebo-controlled study in overweight patients given a herbal preparation containing damiana in combination with maté tea (leaves of Ilex paraguariensis A.St.-Hil.) and guarana (seeds of Paullinia cupana Kunth), which also produced a significant delay in gastric emptying.

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