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Holy Basil: The story of Ocimum Sanctum

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Ocimum sanctum (Holy Basil or Tulsi) is an aromatic herb belonging to the family Lamiaceae.1 It is native to India and south-east Asia where it has been used medicinally for centuries and is now cultivated all over the world, including in Australia.2 Ocimum sanctum has warming and astringent properties,1 and is slightly bitter. In Ayurvedic medicine, Ocimum sanctum is believed to normalise an imbalance of both the kapha and vata doshas.3 While the whole plant (flowers, leaves, and seeds) has medicinal properties, it is mostly the leaves, rich in volatile oils, that are used.

There are two main varieties of Tulsi: a green-leaved variety known as Rama Tulsi and a purple-leaved variety known as Krishna-Tulsi. Both Rama and Krishna Tulsi appear to have similar biochemical and therapeutic properties.2 To date there has been only a small number of published clinical trials examining the effects of Ocimum sanctum in humans, however, those conducted show great promise, confirming the valuable insights of it’s traditional use.

Adaptogen and mood enhancing

In Ayurvedic medicine, Ocimum sanctum was traditionally renowned for being a ‘rasayna’, a concept that describes the rejuvenating and tonic effects a specific herbal medicine may have on the body.


Intake of OciBest®, an extract of Ocimum tenuifl orum (1200 mg/day) for 6 weeks in individuals with perceived high stress resulted in reduced symptoms of overall fatigue and less daytime sleepiness compared to those in the placebo group.4 These findings highlight the adaptive and tonic properties of Holy Basil.

Similarly, in a small randomised controlled trial involving 35 participants with generalised anxiety disorder, 500 mg of Ocimum sanctum consumed twice a day over 60 days improved mood and assisted with stress adaptation. Individuals were assessed clinically as well as via a self- reported questionnaire at three points over 60 days. As well as less depression and anxiety, participants reported better attention to detail, highlighting the cognitive enhancing properties of Ocimum sanctum, with researchers hypothesising that Ocimum sanctum may exert these effects via the regulation of the hypothalamus-pituitary- adrenal (HPA) axis.

A later study by Sampath et al.5 examining the effects of Ocimum sanctum on cognitive parameters in healthy volunteers over 30 days, noted that while there was a significant reduction in salivary cortisol concentrations, the results, while clinically significant, were not statistically significant when compared to the placebo group, suggesting a more complex mechanism of action at play.

Immune enhancing

A literature review examining the safety and efficacy of Ocimum sanctum in humans observed the ability of Ocimum sanctum to enhance immunity in five of the studies reviewed.6 One paper included in the review demonstrated that Ocimum sanctum reduced viral load in the saliva of individuals with herpes virus,6 highlighting its immune- enhancing properties.

Similar immune-enhancing effects were observed in a small randomised controlled trial in healthy adult participants after four weeks of consuming 300 mg/day of Ocimum sanctum leaf extract.7 Increased Natural Killer (NK) and T-helper cells were observed, reflecting an enhanced immune response. Chronic stress reduces the activity of NK cells, subsequently increasing vulnerability to infection.7

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1  Pattanayak P, Behera P, Das D, Panda SK. Ocimum sanctum Linn. A reservoir plant for therapeutic applications: An overview. Pharmacogn Rev. 2010;4(7):95-105. doi:10.4103/0973-7847.65323
2  Pandey V, Swami RK, Narula A. Harnessing the Potential of Roots of Traditional Power Plant: Ocimum. Front Plant Sci. 2021;12:765024. Published 2021 Nov 1. doi:10.3389/fpls.2021.765024
3  Cohen MM. Tulsi - Ocimum sanctum: A herb for all reasons. J Ayurveda Integr Med. 2014;5(4):251-259. doi:10.4103/0975- 9476.146554
4  Saxena R. C., Singh R., Kumar P., et al. Efficacy of an extract of ocimum tenuiflorum (OciBest) in the management of general stress: A Double-blind, Placebo-controlled Study. Evidence-based Complementary and Alternative Medicine. 2012;2012:7. doi: 10.1155/2012/894509.894509
5 Sampath S, Mahapatra SC, Padhi MM, Sharma R, Talwar A. Holy basil (Ocimum sanctum Linn.) leaf extract enhances specific cognitive parameters in healthy adult volunteers: A placebo controlled study. Indian J Physiol Pharmacol. 2015 Jan- Mar;59(1):69-77. PMID: 26571987.
6 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;2017:9217567. doi:10.1155/2017/9217567
7 Mondal S., Varma S., Bamola V. D., et al. Double-blinded randomized controlled trial for immunomodulatory effects of Tulsi (Ocimum sanctum Linn.) leaf extract on healthy volunteers. Journal of Ethnopharmacology. 2011;136(3):452–456. doi: 10.1016/j. jep.2011.05.012.

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Lisa Costa-Bir's picture
Lisa Costa-Bir
Lisa is a practicing naturopath based in Sydney, Australia. She specialises in women’s health and auto-immunity in her clinical work, as well as working as an academic lecturer and clinical supervisor at Torrens University and Endeavour College of Natural Therapies in Sydney. She is also an Adjunct Fellow of the National Centre for Naturopathic Medicine (SCU). She has a Masters of Women’s Health (UNSW), as well as Graduate Diploma of Applied Science in Naturopathy (UWS), and a Bachelor of Applied Science in Naturopathy (UWS). Lisa has written numerous naturopathic articles and was a contributing author for the widely used naturopathic textbooks “Clinical Naturopathic Medicine” and “Advanced Clinical Naturopathic Medicine”. Her greatest passion is psycho-neuro-immunology and understanding how natural interventions can be used to modulate neuro-endocrine-immune responses for optimal patient heath. In her spare time, Lisa enjoys doing Muay Thai, spending time out in nature and making TikTok videos with her daughter and her cat Milo.