Holy basil, also known as Tulsi in hindu or tulasi in Sanskrit, is a highly revered culinary and medicinal aromatic herb from the family Lamiaceae that is indigenous to the Indian subcontinent and been used within Ayurvedic medicine more than 3000 years (1).
It has been called the elixir of life, the queen of herbs, "Liquid Yoga" and as the mother of Natural Medicine, as it has been reported to promote homeostasis and adaptation to stress. Prolonged exercise, exposure to cold and excessive noise disrupt homeostasis causing normal and metabolic stress. Homeostasis is the inability of the human body to adapt to stressors, thus contributing to the dysfunction of the body . It helps the body and the mind to cope with stressors and restore physiological and psychological function (2). While its name is related to common basil, it is not a substitute.
Holy Basil is used ritualistically in Hinduism and in some Greek Orthodox Churches for the creation of holy water (= holy water). Basil contains calcium, vitamin A (= strengthens the immune system) and C, iron (= better oxygenation), zinc and chlorophyll (= strengthens the immune system). The main chemical components of holy basil are Oleanolic acid, Rosmarinic acid, Ursolic acid, Eugenol, Linalool, Carvacrol and β-caryophyllene. Holy Basil has potent anti-inflammatory, antioxidant, anti-stress, and calming, properties.
In India, the Holy Basil has been adopted in spiritual functions and lifestyle practices that provide the human body with many benefits. Many of the physiological benefits of the Holy Basil can be attributed to its ability to help the body's internal storage and protect the body from damage caused by toxins. The Holy Basil has a warm and bitter hue, which is said to penetrate the deep tissues, promoting well-being and endurance .
Holy Basil leaf tea reduces blood sugar and cholesterol
In a study, 40 type 2 diabetes patients were assigned to consume holy basil leaf tea for four weeks. Researchers concluded that consumption of the holy basil tea resulted in significant reduction in fasting blood sugar and postprandial blood sugar, as well as a moderate reduction in cholesterol. 
Holy Basil can benefit mood, ameliorate anxiety and stress
A study in 2008, demonstrated that 500 mg holy basil extract, orally twice daily after a meal for 60 days reduced the effects of generalized anxiety disorder (GAD). A recent review of 24 studies in Evidence Based Complementary and Alternative Medicine examined the therapeutic effects of tulsi in humans. The reviewed studies suggested that tulsi plays a stress-reducing role and can help combat psychological stress and support immunity and neurocognition. 
Holy Basil has immunomodulatory properties
It has been used for bronchitis, cough, asthma, headache, inflammation, rheumatism and pyrexia (1). The leaves of holy Basil contain volatile oils such as eugenol (71%) and methyl eugenol (21%), carvacrol, and sesquiterine hydrocarbon caryophyllene (7). Phenolic compounds are also contained, such as apigenin, and rosmeric acid (7).
A 2011 study of 24 healthy volunteers consumed 300 mg capsules of holy basil leaves or placebo on empty stomachs every day for four weeks, followed by a three-week washout period before crossover to the next intervention. The holy basil group had significantly increased levels of IFN-γ, IL-4, and percentages of T-helper cells and natural killer (NK) cells, showing holy basil’s immunomodulatory effects in humans.
A study on asthmatic patients demonstrated that 500mg of dried holy basil leaves three times daily improved viral capacity and provided relief of asthmatic symptoms in three days (8). In acute viral infections, patients that received daily ten grams of fresh holy basil had increased survival rate (9). Holy basil has been shown to increase immune response by increasing natural Killer (NK) and T-helper cells in healthy adults (4).
1. Jamshidi, N., & Cohen, M. M. (2017). The Clinical Efficacy and Safety of Tulsi in Humans: A Systematic Review of the Literature. Evidence-based complementary and alternative medicine: eCAM, 2017, 9217567.
3. Agrawal P, Rai V, Singh RB. Randomized placebo-controlled single-blind trial of holy basil leaves in patients with non-insulin-dependent diabetes mellitus. Int J Clin Pharmacol Ther. 1996; 34:406-409.
4. Mondal S, Varma S, Bamola VD, Naik SN, Mirdha BR, Padhi MM, et al. Double-blinded randomized controlled trial for immunomodulatory effects of tulsi (Ocimum sanctum Linn.) leaf extract on healthy volunteers. J Ethnopharmacol. 2011;136(3):452-456.
6. Kochhar A, Sharma N, Sachdeva R. Effect of supplementation of Tulsi (Ocimum sanctum) and Neem (Azadirachta indica) leaf powder on diabetic symptoms, anthropometric parameters, and blood pressure of non-insulin dependent male diabetics. Ethno-Med. 2009; 3:5–9.
7. Baliga MS, Jimmy R, Thilakchand KR, Sunitha V, Bhat NR, Saldanha E, Rao S, Rao P, Arora R, Palatty PL. Ocimum sanctum L (Holy Basil or Tulsi) and its phytochemicals in the prevention and treatment of cancer. Nutr Cancer. 2013;65 Suppl 1:26-35.
9. Rajalakshmi S., Sivanandam G., Veluchamy G. Role of Tulsi (Ocimum sanctum Linn.) in the management of Manjal Kamalai (viral hepatitis) Journal of Research in Ayurveda and Siddha. 1986;9(3-4):118–123