Holy Basil
Also known as: Tulsi, Ocimum sanctum, Ocimum tenuiflorum, Sacred Basil
Effective Dosage
300 mg/day leaf extract (limited clinical data; no established optimal range)
What the Science Says
Holy basil (Tulsi) is a traditional herb used in Ayurvedic medicine, now studied as an adaptogen — a plant that may help the body handle stress. One small clinical trial found that 300 mg/day of holy basil leaf extract improved reaction time, reduced errors on cognitive tests, and lowered P300 latency (a brain-response marker) over 30 days. A separate multi-herb trial including holy basil showed reductions in perceived stress, anxiety, and improved sleep quality over 60 days, though holy basil was combined with other herbs in that study, making it hard to isolate its specific contribution.
What It Doesn't Do
Not proven to treat diabetes on its own — the one blood sugar trial from 1996 was small and single-blind. No solid evidence it fights cancer in humans; lab cell-line results don't translate directly to people. Won't repel mosquitoes when taken as a supplement — that research is purely computational. No evidence it improves skin aging when consumed orally. The nanoparticle and wastewater research has zero relevance to human health supplements.
Evidence-Based Benefits
A small placebo-controlled study (PMID: 26571987) found that 300 mg/day of ethanolic holy basil leaf extract improved specific cognitive parameters including reaction time and error rates on cognitive tests, with some reduction in P300 latency. A 1996 crossover trial (PMID: 8880292) reported significant reductions in fasting blood glucose (by ~17.6%) and postprandial blood glucose in patients with non-insulin-dependent diabetes mellitus. Holy basil was also included in a multi-herb adaptogen formula that reduced perceived stress, anxiety, and improved sleep quality compared to placebo (PMID: 41656269), though its individual contribution cannot be isolated from that combination study.
Weak EvidenceEffective at: 300 mg/day ethanolic leaf extract (based on one clinical study; no established optimal dose range from provided papers)
Source: auto-research
Absorption & Bioavailability
Unknown — no pharmacokinetic or bioavailability studies were included in the provided data. Ethanolic leaf extracts were used in the one human cognition trial, which may affect absorption compared to raw leaf or other preparations.
Red Flags to Watch For
- Most provided research is pre-clinical, computational, or industrial — not human health trials
- The only solo human cognition trial was small with no reported sample size details in the abstract
- The stress/sleep trial used holy basil in a multi-herb blend, so its individual effect cannot be confirmed
- The blood sugar trial (1996) was single-blind and small — far below modern evidence standards
- Over 1,000 supplement products contain holy basil, but clinical evidence supporting most label claims is very thin
- No long-term safety data from the provided studies; genotoxicity paper had no available abstract
Products Containing Holy Basil
See how Holy Basil is used in these analyzed products:
Research Sources
- PubMed
- NIH DSLD
This information is for educational purposes only and is not medical advice. Always consult a healthcare professional before starting any supplement regimen. Last updated: 2026-04-06