Tulsi — Ocimum tenuiflorum, holy basil — is the plant of the household in India. Most homes have one growing in the courtyard. The traditional ritual is three leaves in morning tea. The ritual predates the clinical literature by at least two centuries.
The modern review that brings the two registers together is Jamshidi & Cohen 2017 (DOI 10.4103/0975-9476.146554), a systematic review of 24 human trials across metabolic, stress, and immune endpoints. The effects are modest in any single trial and convergent across the set: fasting glucose, perceived stress scores, and some immune markers all move in the right direction.
It's the convergence that is interesting. Single trials can be noise. Twenty-four trials all pointing to small, positive effects — across different endpoints, at different doses, in different countries — is the kind of evidence Ayurveda generally does not get to present, and the kind that warrants daily use rather than episodic.
We include tulsi in Ember Immunity at 300 mg and in Tiny Tulsi, the children's blend, at a lower dose. The traditional three-leaves-a-day is not replaced by this; it complements it. If you have a tulsi plant at home, please keep picking the leaves.
