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Does holy basil (tulsi) help with stress and blood sugar?

Two small trials of standardised holy basil extracts found less stress than placebo. No human trials on blood sugar were found.

Published October 2026

Short answer

Early, limited evidence that a standardised holy basil extract may ease stress. No human trials on blood sugar were found. Evidence grade C (Limited). Two small placebo-controlled trials (about 250 adults in total) of branded extracts; downgraded for small total sample. Blood sugar rests on rat and test-tube studies only.

Key takeaways

  • In an 8-week trial of 100 adults, a holy basil extract lowered perceived stress by 37%, against 19% on placebo [1].
  • A 6-week trial of 150 adults with stress symptoms found about 39% more improvement with a different holy basil extract than with placebo [2].
  • No human trials of holy basil on blood sugar were found; the glucose results come from rats and test tubes [3][4].
  • Both trials tested extracts made by the same company, Natural Remedies, so independent trials are still needed [1][2].

The short version

Holy basil, also called tulsi, may help with stress. Two small, placebo-controlled trials of standardised extracts found lower stress scores than placebo [1][2]. For blood sugar, we found no human trials; the evidence comes from rats and test tubes [3][4].

What the studies show

In an 8-week trial of 100 adults under stress, a holy basil extract lowered perceived stress by 37%, against 19% on placebo. Scores on a sleep questionnaire fell 48% on the extract and 27% on placebo, but a sleep tracker showed no difference between the groups [1].

A 6-week trial of 150 adults with stress symptoms used a different extract at 1,200 mg a day. It found about 39% more improvement in stress symptoms than placebo [2].

Blood sugar is different. In diabetic rats, a holy basil extract lowered fasting blood sugar over eight weeks [3]. In test tubes, extracts blocked enzymes that break down starch into sugar [4]. A 2017 review says human tulsi studies reported benefits for diabetes, but it does not name them, and we could not check them [5].

The nuances

The trials were small and short, lasting 6 to 8 weeks. Side effects were rare and similar in both groups in the 2022 trial [1]. An earlier open-label trial in 35 people with anxiety had no placebo group, so it cannot show the extract caused the change [6][1].

A placebo-controlled trial in healthy adults found faster reaction times on memory and attention tests with 300 mg a day of leaf extract. Its anxiety and cortisol improvements appeared only within the holy basil group [7].

Both main trials used branded extracts made by Natural Remedies, which funded or supplied them. Results from these extracts do not show that tea or other products work the same way [1][2].

A 2026 trial of a blend of holy basil with Rhodiola and Schisandra also reported lower stress. Because it was a mixture, its results cannot be credited to holy basil alone, and some authors had ties to a supplement company [8].

What this means for you

For stress, the evidence so far is early and limited to a few trials of one type of extract. For blood sugar, the only evidence is from rats and test tubes [3][4].

Reviews advise against high doses during pregnancy or breastfeeding [9]. The stress trials excluded people taking regular medicines, so interactions are not well studied [1]. If you take medicines or are pregnant, talk to a doctor before using holy basil. Read more on the holy basil topic page.

Go deeper

  • Holy Basil — Holy basil extract may ease perceived stress: two small placebo-controlled trials found lower stress scores than placebo.

References

  1. A randomized, double-blind, placebo-controlled trial investigating the effects of an Ocimum tenuiflorum (Holy Basil) extract (HolixerTM) on stress, mood, and sleep in adults experiencing stress.. Front Nutr, 2022.
  2. Efficacy of an Extract of Ocimum tenuiflorum (OciBest) in the Management of General Stress: A Double-Blind, Placebo-Controlled Study.. Evid Based Complement Alternat Med, 2012.
  3. Hypoglycaemic, hypolipidemic and antioxidant properties of tulsi (Ocimum sanctum linn) on streptozotocin induced diabetes in rats.. Indian J Clin Biochem, 2001.
  4. Antidiabetic Indian plants: a good source of potent amylase inhibitors.. Evid Based Complement Alternat Med, 2011.
  5. The Clinical Efficacy and Safety of Tulsi in Humans: A Systematic Review of the Literature.. Evid Based Complement Alternat Med, 2017.
  6. Controlled programmed trial of Ocimum sanctum leaf on generalized anxiety disorders.. Nepal Med Coll J, 2008.
  7. Holy basil (Ocimum sanctum Linn.) leaf extract enhances specific cognitive parameters in healthy adult volunteers: A placebo controlled study.. Indian J Physiol Pharmacol, 2015.
  8. Effects of multi-herb and ashwagandha root formulas on stress modulation: a randomized, double-blind, placebo-controlled clinical study.. Trials, 2026.
  9. The Safety and Efficacy of Botanicals with Nootropic Effects.. Curr Neuropharmacol, 2021.