Ingredient Evidence Review
Sceletium tortuosum (Zembrin®)
Sceletium tortuosum (kanna)
Last updated 2026-05-19 · 3 primary citations
Mechanism
Zembrin® is a standardized extract of the South African plant kanna. It takes the edge off acute stress quickly — brain-imaging studies show it quiets the threat-detection circuitry — but without sedating you. The point is calmer, not slower.
Why we use it
High-stakes focus often requires acute anxiety modulation. Zembrin is the only botanical with replicated fMRI amygdala-decoupling signal at supplement doses.
How we dose it
Hericea uses 25 mg per serving (per AM stick pack). The clinical trial range that anchors this dose is 25–50 mg/day.
At the Zembrin® clinical RCT dose. Mesembrine-alkaloid-standardized branded form.
Quality & sourcing
Zembrin® HG&H Pharmaceuticals branded; mesembrine-alkaloid standardized.
HG&H Pharmaceuticals-licensed.
Cautions
- consult physicianConsult physician if on SSRI/SNRI/MAOI antidepressants.
Primary literature
Terburg et al. (Northumbria) (2013)
NeuropsychopharmacologyfMRI RCT
Zembrin decoupled amygdala-hypothalamus reactivity to fearful faces.
Reay et al. (2020)
RCTRCT · 1 weeks
Acute Zembrin improved cognitive performance under stress.
Systematic review (2024)
Meta-analysisMeta-analysis
SMD 0.35 across Sceletium cognitive-mood endpoints.