Limited evidence. Direction: Benefit.
Evidence maturity: Early signalShort-term onlySingle research group
Rubric condition met: C: one small RCT (n = 40) in healthy adults with positive results on task measures
One placebo-controlled trial in 40 healthy adults aged 18-30 found faster responses and fewer errors on the Sternberg working-memory task and the Stroop task after 300 mg/day of an ethanolic leaf extract for 30 days. Both groups improved, and the placebo group plateaued after day 15. The abstract gives no effect sizes, funding is not stated, and no replication was found (PubMed searches, November 11, 2026). Stroop results (executive function) are not graded separately.
Evidence maturity: Early signal One RCT of 40 adults aged 18-30 with funding not stated (unknown is never treated as independent).
Tested as: Holy basil leaf extract
Science is provisional. This grade reflects the evidence we found as of . Next review: .
Maturity sits beside each grade. The grade says what the evidence shows; maturity says how much of it there is and how well it is confirmed.
| Study | Year | Design | Participants | Result |
|---|---|---|---|---|
| Sampath 2015 | 2015 | RCT | 40 | result not recorded |
| Jamshidi 2017 | 2017 | meta-analysis | not recorded | result not recorded |
Jamshidi N, Cohen MM. The Clinical Efficacy and Safety of Tulsi in Humans: A Systematic Review of the Literature Evid Based Complement Alternat Med, 2017. PMID 28400848
Sampath S, Mahapatra SC, Padhi MM. Holy basil (Ocimum sanctum Linn.) leaf extract enhances specific cognitive parameters in healthy adult volunteers: A placebo controlled study Indian J Physiol Pharmacol, 2015. PMID 26571987
Search (): (holy basil[tiab] OR tulsi[tiab] OR "Ocimum sanctum"[tiab] OR "Ocimum tenuiflorum"[tiab]) AND (cognitive[tiab] OR cognition[tiab] OR memory[tiab] OR attention[tiab] OR "reaction time"[tiab]) AND (randomized[tiab] OR placebo[tiab])
A, strong: what grade A means
At least one meta-analysis or three independent randomized trials in the relevant healthy population, pointing the same way, with low or some risk of bias, at doses legally available.
B, moderate: what grade B means
Two or more randomized trials with mostly consistent results, or one large, well-run trial, or a meta-analysis with high heterogeneity.
C, limited: what grade C means
One small randomized trial, open-label or pilot studies, or results only in clinical or older populations being applied to healthy adults.
D, preliminary: what grade D means
Animal, cell or mechanism evidence only. No controlled human outcome data.
N, no benefit shown: what grade N means
Adequate human randomized trials found no meaningful effect.
