Double-blinded randomized controlled trial for immunomodulatory effects of Tulsi (Ocimum sanctum Linn.) leaf extract on healthy volunteers

J Ethnopharmacol. 2011 Jul 14;136(3):452-6. doi: 10.1016/j.jep.2011.05.012. Epub 2011 May 17.


Ethnopharmacological relevance: Tulsi (Ocimum sanctum Linn.) is considered as a sacred herb and traditionally it is believed that consumption of Tulsi leaf on empty stomach increases immunity. Experimental studies have shown that alcoholic extract of Tulsi modulates immunity.

Materials and methods: The present study was designed to evaluate the immunomodulatory effects of ethanolic extract of Tulsi leaves through a double-blinded randomized controlled cross-over trial on healthy volunteers. Three hundred milligrams capsules of ethanolic extracts of leaves of Tulsi or placebo were administered to 24 healthy volunteers on empty stomach and the results of 22 subjects who completed the study were analyzed. The primary objective was to study the levels of Th1 and Th2 cytokines (interferon-γ and interleukin-4) during both pre and post intervention period in blood culture supernatants following stimulation with lipopolysaccharide and phytohaemagglutinin. Other immunological parameters such as T-helper and T-cytotoxic cells, B-cells and NK-cells also were analyzed using Flowcytometry.

Results: Statistically significant increase in the levels of IFN-γ (p=0.039), IL-4 (p=0.001) and percentages of T-helper cells (p=0.001) and NK-cells (p=0.017) were observed after 4 weeks in the Tulsi extract intervention group in contrast to the placebo group.

Conclusions: These observations clearly ascertain the immunomodulatory role of Tulsi leaves extract on healthy volunteers.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Cross-Over Studies
  • Double-Blind Method
  • Female
  • Hemagglutinins
  • Humans
  • Immunologic Factors / pharmacology*
  • Interferon-gamma / blood*
  • Interleukin-4 / blood*
  • Killer Cells, Natural / metabolism*
  • Lipopolysaccharides
  • Male
  • Ocimum*
  • Plant Extracts / pharmacology*
  • Plant Leaves
  • Reference Values
  • T-Lymphocytes, Helper-Inducer / metabolism*
  • Young Adult


  • Hemagglutinins
  • Immunologic Factors
  • Lipopolysaccharides
  • Plant Extracts
  • Interleukin-4
  • Interferon-gamma