This post summarizes “Sceletium tortuosum: A review on its phytochemistry, pharmacokinetics, biological, pre-clinical and clinical activities” by Olatunji et al., published in the Journal of Ethnopharmacology (2022). Read the full review.
Scope
The review covers research on kanna (Sceletium tortuosum) published mainly between 2009 and 2021: its recorded traditional uses, its chemistry, how its alkaloids move through the body, and the laboratory and clinical work done so far.
Traditional use and cultivation
The review records centuries of use among the Khoikhoi and San peoples — fermented preparations, endurance during hunts, social rituals, and trade. Commercial cultivation began in 1996 and has expanded across South Africa and Namibia.
Chemistry
Twenty-five alkaloids in four structural classes — mesembrine, Sceletium A4, joubertiamine, and tortuosamine — have been identified, with the mesembrine class predominant. Alkaloid content varies with cultivation, processing, and extraction method — which is why analytical methods like HPLC and GC-MS matter, and why extracts are made to stated alkaloid targets.
Pharmacokinetics
Data are limited but consistent: rapid absorption, quick metabolism of mesembrine, peak plasma concentrations within hours in human trials, no accumulation over repeated servings, and alkaloids that cross the blood-brain barrier.
Laboratory and clinical findings
Laboratory studies report antioxidant activity and effects on serotonin uptake, PDE4, and GABA binding. Clinical studies — all in healthy adults — report good tolerability at servings up to 25mg of a standardized research extract, measurable changes in cognitive test performance, and changes in EEG and fMRI responses to cognitive and emotional tasks.
The review notes that no studies have been run in medical conditions. The research so far is about healthy people.
Limits
Alkaloid content varies between products, pharmacokinetic data remain thin, and the clinical work is early. The authors call for expanded trials, sustainable cultivation, and more mechanistic study.
†These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
