Tulsi (Holy basil) - a scientific overview

General Information

Botanical Name: Ocimum sanctum, Ocimum tenuiflorum (synonym)

Common Name: Holy basil, sacred basil, surasa (Sanskrit), tulsi or tulasi (Hindi)

Parts Used: Whole plant, leaf (common)

Cultivation: Tulsi is a perennial plant that grows wild throughout India and is also found in countries such as China, Malaysia, Pakistan and Thailand. It tends to favor tropical and subtropical climates but can grow in cooler climates as well. (1)(2)(3)

Phytochemical Constituents: Volatile oil from the leaf contains eugenol, euginal, carvacrol, linalool, limatrol, methyl chavicol, caryophyllene. It also contains triterpenes (such as ursolic acid), fatty acids and sitosterols.(1)(4)

Nutritional Value: Calcium, chlorophyll, iron, vitamin A, C and zinc (4)

Tulsi - Ocimum sanctum

Traditional Uses

Tulsi is an aromatic herb from the Lamiacea family that is considered to be one of the most sacred plants in Hinduism.(5)(6)(8) It has been worshiped and used in spiritual rituals for thousands of years and is a common house hold item throughout India. This plant is very important and often used in Ayurveda, a traditional system of medicine that believes in the balance between mind, body and spirit. It is referred to as “The Queen of Herbs,” “Incomparable One,” and “Mother Medicine of Nature” due to the multiple benefits it provides. (6)(7) In fact, it is considered to be the “Elixir of Life,” traditionally being used as a tonic for the body, mind and spirit. (6)(7)

Ayurveda considers Tulsi to be an herb with hot and bitter properties “which has been used to help dry tissue secretions due to its ability to penetrate deep into tissue” while also offering pulmonary and digestive support. (6)

It has traditionally been used as an adaptogen to help counteract the physical, biological and emotional effects of stress.(6) Others like to think of it as a “liquid form of yoga” providing relaxation, clarity of thought and memory enhancement. (6) Tulsi helps to balance kapha and vata doshas while promoting longevity and wellness if taken regularly. (6)

Other traditional uses of this herb include anxiety, arthritis, common cold, inflammation, dermal, oral, gastrointestinal and genitourinary conditions as well as malaria and insect bites. It is often consumed as a tea, fresh leaf, dried powder or topically as an essential oil. (4)(6)(7)(9)(10)

Research Review

Antimicrobial and Antifungal Properties

A study which evaluated the effects of Ocimum sanctum essential oil against bacteria showed it to inhibit the growth of Escherichia coli, Bacillus anthracis and Pseudomonas aeruginosa in vitro. (9)(14) It was also found to have antifungal properties against Aspergillus niger.(9)(14) Other studies have seen similar results against Mycobacterium tuberculosis and Staphylococcus aureas. (6) (12)(13)

A clinical trial tested the effects of Ocimum sanctum against oral Streptococcus mutans which has been associated with tooth decay. The study suggested that when used as an oral rinse, it “may be as effective as 0.2% Chlorhexidine and Listerine.” (6)(11)

Antiviral Properties

A study was conducted to evaluate the antiviral properties of Ocimum sanctum leaf and Acacia arabica against Avian Influenza virus (H9N2) using an in-ovo model. (15) The crude extract, terpenoid and polyphenols of Ocimum sanctumwere specifically tested. The study found that all three were effective in limiting H9N2 virus replication at 24, 48, and 72-hour time intervals post inoculation. The crude extract and terpenoids of Ocimum sanctum showed to significantly decrease the virus genome copy numbers. (15)

In another study, Ocimum sanctum was tested on patients with acute viral encephalitis to determine whether it had any antiviral properties while another group of patients were given dexamethasone. (5)(17)(18) At the end of four weeks, the group taking Ocimum sanctum showed to have an increased survival rate compared to the other group. .(5)(17)(18) A similar study evaluating Ocimum sanctum’s effect on viral hepatitis showed improvements in symptoms after two weeks.(5)(17)(18)

Asthma Support

A single-blind, cross-over study tested the effects of Ocimum sanctum in patients with mild to moderate asthma to observe any potential bronchodilator activity. (18) The results showed that 200 milligrams of Ocimum sanctum given twice daily improved symptoms as well as FEV1 and PEFR values which suggested that the herb may possess bronchodilator properties. (18)

Cognitive Enhancement

A study comparing Ocimum sanctum to a placebo group was performed to evaluate its effects on stress and cognition.(19) A dose of 300 milligrams (ethanolic leaf extract) was tested over a period of 30 days. The Sternberg and Stroop test were used to measure cognitive processing with initial improvements seen in both groups. By day 15, the placebo group had stabilized while the Ocimum sanctum group showed significant improvements in the following cognitive parameters: (19)

Sternberg test: reaction time, error rate

Stroop test: reaction time and error rate of interference task

Immune Modulation

A study evaluating the immunological effects of Tulsi leaves (Ocimum sanctum, ethanolic extract) was conducted over a four-week period. (20) Participants were either given 300 milligrams of the herb or placebo on an empty stomach. At the end of the four-weeks, individuals who took Tulsi had a “significant increase in IFN-g, interleukin-4 as well as a percent increase in T-Helper cells and Natural Killer cells when compared to the placebo volunteers.” (20) This suggests Tulsi may play a role in immune modulation.

Lowers Serum Lipid Levels While Protecting Liver and Heart Tissue

An animal study evaluating the effects of Ocimum sanctum leaf extract on lipid levels was conducted over a seven-week period. (21) Three groups of rats were evaluated: rats who were fed a normal diet, rats who were fed with a high-cholesterol diet, and another group fed with a high-cholesterol diet along with daily consumption of Ocimum sanctum.(21)

The study reported that at the end of seven-weeks, the rats treated with Ocimum sanctum had “suppressed high levels of hepatic lipid and serum lipid profile without significant effects on fecal lipid excretion. An increase in fecal bile acid excretion was observed as well as a significant decrease in ALT, AST, AP, LDH and CK-MB”. (21) Upon histological evaluation, liver and myocardial tissue was preserved in this group, despite the high-cholesterol diet. (21)

Metabolic Disorder Regulation

A study evaluated the effects of Ocimum sanctum on a group of individuals with type 2 diabetes. (22) The first group was given 5 milligrams of Glibenclamide with food per day while the second group was given 250 milligrams of Ocimum sanctum in addition to Glibenclamide.

Reported results and data listed below:

  • Fasting Blood Glucose Levels:
    • By day 90, the group who received Glibenclamide alone had a reduction of 34.32% while the group who took Glibenclamide with Ocimum sanctum dropped by 39.66% (22)
  • Post-Prandial Blood Glucose Levels:
    • By day 90, the group who received Glibenclamide alone had a mean reduction of 38.53% while the group who took Glibenclamide with Ocimum sanctum had a mean reduction of 43.68 % (22)
  • Glycosylated Hemoglobin (HbA1c):
    • By day 90, the group who received Glibenclamide with Ocimum sanctum had lower glycosylated hemoglobin (HbA1C) levels than the group taking Glibenclamide alone (22)

Study Data: (22)

Day 1

Fasting Blood Glucose Levels

Day 90

Fasting Blood Glucose Levels

Day 1

Post-Prandial Blood Glucose Levels

Day 90

Post-Prandial Blood Glucose Levels

Day 1

Glycosylated Hemoglobin (HbA1c)

Day 90

Glycosylated Hemoglobin (HbA1c)

Glibenclamide (alone)

174.34 gm/dl

114.50 gm/dl

247.31 gm/dl

152.02 gm/dl



Glibenclamide plus Ocimum sanctum

171.53 gm/dl

103.50 gm/dl

254.13 gm/dl

143.12 gm/dl



Stress Support

A double-blind, placebo-controlled study was conducted to determine whether Ocimum tenuiflorum (synonym: Ocimum sanctum) could demonstrate stress symptom control. (23) Participants were either given OciBest, an extract of Ocimum tenuiflorum at 1,200 milligrams per day for six weeks or a placebo. After six weeks, the group taking OciBest showed a 39% improvement in stress control compared to the placebo group. (23) Symptoms monitored included exhaustion, sexual dysfunction, difficulty sleeping and forgetfulness. (23) A separate study reported a reduction in serum cortisol concentration when 500 milligrams of Ocimum sanctum was evaluated in an animal study which also suggests it may support stress response. (24)

Safety Information:

Safety Class: 1

Interaction class: A

No known contraindications, drug or supplement interactions.


Temporary reduction in sperm count and motility has been reported in animal studies. (25)(26)(27)(28)(30)

Another animal study evaluating the effects Ocimum sanctum (500 mg/kg) on thyroid function reported a reduction in thyroxine (T4) serum levels. (25)(29)

Pregnancy: A reduction in full-term pregnancies and litter size was reported in a study of female rats when 2 g/kg and 4 g/kg were administered orally. (25)(30)

Lactation: Safety information has not been established at this time.


This research review article is sponsored by The Wise Woman Herbals® Practitioner Learning Community. The information provided is solely on behalf of the author and not Wise Woman Herbals®. The purpose of this article is to provide a summary of clinical or scientific information that has been published about this specific herb. This information has not been approved by the FDA nor is it intended to cure, treat or replace medical care. Always consult with a health care provider before starting a new wellness regimen.


Yasamine Farshad, NDDr. Yasamine Farshad is the Practitioner Education Manager for Wise Woman Herbals® where she coordinates educational events and content for health care practitioners. Dr. Farshad received her Doctorate in Naturopathic Medicine from the Southwest College of Naturopathic Medicine in Tempe, Arizona and received her Bachelor of Science in Ecology and Evolutionary Biology from the University of Arizona. Dr. Farshad also teaches anatomy and physiology for Herbal Wisdom Institute where she received her herbalist certification. She focuses in nature cure using botanical medicine and nutrition.


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