Kanna extract,
does it really help with Relief of stress and anxiety?
research showsA meta-analysis of four randomized trials and 117 participants found no anxiety benefit from kanna: RR 1.01 (95% CI 0.56-1.83, p=0.98). Positive findings are limited to an fMRI surrogate in 16 people and selected time points in a 20-person laboratory-stress study. Nell 2013 was a safety trial without prespecified efficacy variables and is excluded from efficacy evidence; the small literature supports D rather than F, with 35 points.
ads claimMarketing links traditional mood support, serotonin-reuptake and PDE4 mechanisms, calmness, and focus to clinical anxiety relief. Direct evidence mostly consists of acute healthy-volunteer studies and surrogate outcomes using the branded Zembrin extract.
Useful facts when choosing a product
- Most efficacy studies used a single 25 mg dose or short-term Zembrin exposure.
- A three-month 37-person trial was designed for safety and did not prespecify efficacy variables.
- The 2023 meta-analysis found no anxiety difference from placebo across four trials with 117 participants.
- Safety data for combination with serotonergic medicines are limited because of possible serotonergic activity.
What the research actually shows
The Terburg 2013 crossover trial gave a single 25 mg dose of Zembrin to 16 healthy participants and reported lower amygdala threat reactivity and amygdala-hypothalamus coupling. Reay 2020 conducted two experiments in 20 healthy young adults; the first multitasking experiment found no treatment effect, while the second simulated public-speaking task found selected subjective-anxiety and heart-rate interaction signals. The Gouhie 2023 meta-analysis pooled four randomized trials with 117 participants and reported anxiety RR 1.01, 95% CI 0.56-1.83, p=0.98, showing no difference.
Why this is classified as D (35)
The anxiety result in a meta-analysis of four randomized trials and 117 participants was null, while positive signals were confined to a 16-person fMRI surrogate and selected points in a 20-person laboratory study, supporting D with 35 points. Nell 2013 is excluded from efficacy evidence because it prespecified no efficacy variables.
Counterpoint. A limited signal remains for acutely induced anxiety responses and threat-processing circuitry in the laboratory.
Rejudgment record. Reassessment (cross-check reflected) — Acute neuroimaging and laboratory-stress signals in 16 to 20 healthy participants conflict with a null meta-analysis of four randomized studies and 117 participants; no confirmatory clinical anxiety-disorder trial exists
Cross-check — Codex and Claude
Evidence Table
| Study | Design | Sample | Funding | Endpoint | Result | Weight |
|---|---|---|---|---|---|---|
| Terburg D et al. 2013 | Randomized double-blind placebo-controlled crossover fMRI trial | 16 | Linked to the Zembrin developer | Amygdala threat reactivity and connectivity | A single 25 mg dose reduced amygdala reactivity and amygdala-hypothalamus coupling. | Supportive |
| Reay J et al. 2020 | Two double-blind placebo-controlled experiments | 20 | Participation by an author from the branded-ingredient company | Laboratory stress, subjective anxiety, heart rate, and skin conductance | The first experiment was negative; the second public-speaking task showed selected anxiety and heart-rate signals. | Supportive |
| Gouhie FA et al. 2023 | Systematic review and meta-analysis | 117 | Unknown | Anxiety outcome | RR 1.01, 95% CI 0.56-1.83, p=0.98, showing no difference from placebo. | Key |
| Nell H et al. 2013 | Randomized double-blind placebo-controlled safety trial | 37 | Linked to the Zembrin developer | Three-month safety and tolerability | Doses of 8 mg and 25 mg were generally tolerated, but no efficacy variables were prespecified. | Safety |
Receipt — 4 References
All 4 cited sources were verified for existence at the original page (as of 2026-07-11).
Reviewed and approved: Chamgap Editorial Team · Approval date: 2026-07-11 · Corrections: none
Cite this verdict
[Chamgap] Kanna extract (Sceletium tortuosum) x Relief of stress and anxiety — Evidence Grade D·35. 4 cited sources checked. Source: https://health-receipt.pages.dev/en/verdicts/mood/kanna-stress-anxiety/ · CC BY 4.0CC BY 4.0 — free to use with attribution; do not distort grades, numbers, or verdict meaning.
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Chamgap is an information source. It reports what research has and has not confirmed; it does not tell readers what to take or buy. That decision belongs to readers and, when needed, medical or legal professionals. This verdict reflects literature available up to the search date and may change as new research appears. Nothing here is medical advice.