Kanna

date revised: January 26, 2026

Kanna (Sceletium tortuosum) is a South African succulent traditionally chewed or brewed to relieve stress, elevate mood, and reduce pain. Modern research attributes these effects mainly to alkaloids found in the plant, including mesembrine, mesembrenone, and mesembrenol, which act as serotonin-reuptake inhibitors and may also inhibit phosphodiesterase-4 (PDE4). In the case of mesmerbine, believed to be the primary stimulating alkaloid in Kanna, increasing serotonin release may also contribute to the effect. Early clinical and preclinical evidence provide a basis for the anxiolytic (anxiety-reducing), mood-supporting, and procognitive effects of Kanna [1]. 

Anxiety & Stress

Controlled human studies and acute experimental work indicate that standardized S. tortuosum extracts can reduce subjective and physiological markers of stress and anxiety in healthy volunteers [2]. A randomized, placebo-controlled trial of the extract Zembrin® found it to be well tolerated and suggested stress-reducing effects, and an fMRI study showed reduced amygdala reactivity after acute administration [3][4].

Mood Enhancement

Preclinical models and several small human studies point to antidepressant-like activity, plausibly mediated by serotonin reuptake inhibition and release [5]. However, evidence for antidepressant efficacy in clinical populations is limited, and larger randomized trials are needed [1].

Procognitive effects

Some trials report modest improvements in cognitive domains such as processing speed, attention, and psychomotor performance after Kanna supplementation EEG studies suggest measurable effects on brain electrical activity consistent with reduced anxiety and improved cognitive state [4]. These findings are preliminary but align with the plant’s reputation for enhancing social and mental clarity.

How does Kanna work?

The primary active alkaloids (mesembrine family) inhibit the serotonin transporter (SERT), producing SRI-like effects in vitro. Select mesembrine-type alkaloids (notably mesembrenone) also show PDE4 inhibitory activity, which could complement serotonergic effects by modulating intracellular signaling and neuroplasticity [5]. Additionally, mesembrine itself has been demonstrated to induce the release of serotonin from neurons [6]. It is possible that the serotonin-releasing effects of mesembrine contribute to the acute effects of Kanna at moderate to high doses, whereas SRI effects resulting from a combination of other alkaloids at lower doses may be responsible for its longer-term impact on mood.

 

Sources

  1. Brendler, T., Brinckmann, J. A., Feiter, U., Gericke, N., Lang, L., Pozharitskaya, O. N., Shikov, A. N., Smith, M., & Wyk, B. V. (2021). Sceletium for Managing Anxiety, Depression and Cognitive Impairment: A Traditional Herbal Medicine in Modern-Day Regulatory Systems. Current neuropharmacology, 19(9), 1384–1400. https://doi.org/10.2174/1570159X19666210215124737

  2. Reay, J., Wetherell, M. A., Morton, E., Lillis, J., & Badmaev, V. (2020). Sceletium tortuosum (Zembrin®) ameliorates experimentally induced anxiety in healthy volunteers. Human Psychopharmacology: Clinical and Experimental, 35(5), e2753. https://doi.org/10.1002/hup.2753

  3. Nell, H., Siebert, M., Chellan, P., & Gericke, N. (2013). A randomized, double-blind, parallel-group, placebo-controlled trial of Extract Sceletium tortuosum (Zembrin) in healthy adults. Journal of alternative and complementary medicine (New York, N.Y.), 19(11), 898–904. https://doi.org/10.1089/acm.2012.0185

  4. Dimpfel, W., Gericke, N., Suliman, S., & Chiegoua Dipah, G. N. (2017). Effect of Zembrin® on brain electrical activity in 60 older subjects after 6 weeks of daily intake: A prospective, randomized, double-blind, placebo-controlled, 3-armed study in a parallel design. World Journal of Neuroscience, 7(1), 72–85. https://doi.org/10.4236/wjns.2017.71011

  5. Olatunji, T. L., Siebert, F., Adetunji, A. E., Harvey, B. H., Gericke, J., Hamman, J. H., & Van der Kooy, F. (2022). Sceletium tortuosum: A review on its phytochemistry, pharmacokinetics, biological, pre-clinical and clinical activities. Journal of ethnopharmacology, 287, 114711. https://doi.org/10.1016/j.jep.2021.114711

  6. Coetzee, D. D., López, V., & Smith, C. (2016). High-mesembrine Sceletium extract (Trimesemine™) is a monoamine releasing agent, rather than only a selective serotonin reuptake inhibitor. Journal of ethnopharmacology, 177, 111–116. https://doi.org/10.1016/j.jep.2015.11.034