Kanna (Sceletium tortuosum) is a low-growing succulent plant native to South Africa. Kanna belongs to the Aizoaceae (fig-marigold) family of plants. Other common names for the plant include channa and kougoed. The plant has been traditionally used in part of Africa as a mood altering herb. Kanna has been used medicinally as a substance that is able to alter appetite by inducing satiety and also as a pain relieving substance. However, the herb may also have sedative and anxiolytic properties that make it useful in the treatment of generalised anxiety disorder (GAD). Reports suggest that Kanna reduces fear, stress and tension. The herb was traditionally chewed, but more recently tablets, teas capsules, tinctures and extracts (Zembrin) are more commonly used to administer the herb. A number of alkaloids have been identified fromt Kanna, and these may explain the mood altering effects of the herb. Alkaloids identified include mesembrine, mesembrenone, mesembranol, tortuosamine and sceletenone.
Kanna (Sceletium tortuosum) has been used traditionally as a mood altering substance in parts of Africa. The herb may have sedative and anxiolytic effects, but other effects are apparent in the herb that may limit its usefulness. The anxiolytic and sedative properties of the herb may be due to the presence of an alkaloid phytochemical component called mesembrine. Animal experiments however show that at doses required clinically to produce anxiolytic activity, there may be other effects present including ataxia. Studies on humans do show the herb is safe at moderate doses, but it is unclear if the herb is effective at favourably altering mood at these doses (8 to 25 mg of the standardised extract called Zembrin). Certainly in studies, some positive mood altering effects have been noticed at moderate doses in healthy human subjects. In particular subjects have reported improved sleep and a decrease in the perception of stress. Therefore although interesting and promising, further research needs to be performed before the herb can be recommended for treating anxiety and depression. There are certainly other more useful and more thoroughly researched herbs that should be considered first. Image from: By Tommi Nummelin (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons.
Evidence for the effectiveness of kanna as an anxiolytic agent are very limited in the scientific literature. However, those studies that have been published tend to support the anecdotal evidence gathered from traditional medicine. The alkaloids in kana have been shown to acts a serotonin uptake inhibitors and in this way may be able to increase serotonin concentrations in the brain, much like the selective serotonin reuptake inhibitor (SSRI) antidepressant drugs, which work in the same way. Of the alkaloids present, mesembrine appears to have the greatest effect in this regard, with mesembrenone having a similar but weaker effect. The mesembrine content of kanna is somewhere between 0.3 and 0.86 % of the plant material, but this may vary with growing conditions and processing. Studies have investigated the safety of kanna on healthy subjects and concluded that extracts of the herb at doses of 8 mg and 25 mg per day for 3 months are well tolerated and showed no adverse effects above those seen by the placebo.
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