Kanna

Botany — a succulent of the South African desert

Kanna is Sceletium tortuosum, of the family Aizoaceae (the "iceplants" or ficoids), a lineage of succulents adapted to the arid soils of South Africa (Schultes, Hofmann & Rätsch, Plants of the Gods, p. 55-56). Recent taxonomy has sometimes reclassified her under Mesembryanthemum tortuosum — both names designate the same plant. She is a low, creeping succulent with fleshy leaves, whose genus name Sceletium refers to the "skeletal" veins visible on the dried leaves. Her common Afrikaans name, kougoed, means "thing to chew". The plant is also known as channa.

Descriptive phytochemistry — the mesembrine alkaloids

The active principles of kanna are mesembrine-type alkaloids: mesembrine, mesembrenone, mesembrenol, and more minor compounds (tortuosamine, channaine, hordenine). Schultes-Hofmann note that these alkaloids of the Mesembryanthemaceae possess a documented sedative activity (Plants of the Gods, p. 71; see also Rätsch & Müller-Ebeling, Encyclopedia of Aphrodisiacs, p. 378-379).

The fermentation does not only preserve the plant: it recomposes her chemical profile. Over the days of sun exposure, the mesembrine content drops sharply — on the order of 1.3% to 0.05% over some ten days in a controlled fermentation (Patnala & Kanfer, 2009, Journal of Ethnopharmacology) — and the balance of alkaloids shifts. This is why traditional fermentation is described as inseparable from the medicine: the simply dried plant does not have the same profile.

What the studies report

Rätsch ranks kanna among the non-hallucinogenic psychoactives. Contemporary research describes several mechanisms: a serotonin reuptake inhibition (SSRI-like effect) and a phosphodiesterase-4 (PDE4) inhibition (Terburg et al., 2013). An fMRI study published in 2013 on a standardised Sceletium extract (Zembrin) reports an attenuation of amygdala reactivity to fearful faces; other trials, at low dose, look at cognitive function and tolerability. These trials are run on the standardised Zembrin extract, often co-authored or funded by its developer — not on the fermented leaf.

These data are descriptive and preliminary: they describe laboratory and imaging observations, not a medical use nor a promise of efficacy. Kanna is not a medicine and does not replace any treatment.

Critical safety note — serotonin

Because kanna acts on serotonin, she must never be combined with serotonergic antidepressants (SSRI, SNRI, MAOI, tricyclics), tramadol, triptans, lithium or MDMA: the cumulation exposes to a potentially serious serotonin syndrome. This precaution comes from the real pharmacology of the plant. After stopping an antidepressant, a washout window of several weeks is necessary before considering kanna, and always with medical advice.

Long lineage

The Khoisan — which gathers the San (hunter-gatherers) and the Khoikhoi (pastoralists) — count among the oldest populations of southern Africa, present for tens of thousands of years (Chennells, 2013). To receive kanna is to enter an ancient transmission that precedes writing, agriculture and the first cities.

In the ethnographic documentation (Manganyi et al., 2021; Rätsch & Müller-Ebeling, p. 378), kanna appears in social communion, in erotic use and in the restoration of those whom grief has emptied.

Modern history — from oblivion to rediscovery

After the colonial mentions of van Riebeeck (1662) and van der Stel (1685), and the praise of the naturalist Peter Kolb (1738), kanna disappears from the European materia medica for nearly two centuries. Her rediscovery at the end of the 20th century culminates with the development of the standardised extract Zembrin by HG&H Pharmaceuticals, marketed under a benefit-sharing agreement with the South African San Council — which passes half of it to the nama communities of Nourivier and Paulshoek — a precedent often cited in matters of bioprospecting respectful of indigenous sovereignty.

Safety and use

Beyond the major serotonergic contraindication, kanna asks for measure. At excessive dose, reports describe nausea, dizziness, headaches and an emotional flattening that follows the peak — the plant "punishes greed". The wisdom of use favours small regular doses and short cures with pauses rather than large occasional intakes. Kanna rather discourages her own abuse.