When I first heard the term ‘liquid yoga’, I was hooked. I had no idea what it actually meant, but I was intrigued. Especially if liquid yoga had anything to do with drinking my way to a double whammy of feeling calm and looking great.

It turns out that ‘liquid yoga’ is the name given to a drink of Holy Basil or Tulsi.

Can I really throw away my yoga mat? It sounds like a great topic for a Healthy But Smart article to me.

What is Holy Basil?

Ocimum sanctum is an Indian medicinal plant that belongs to the Lamiaceae family (1). It is known as Tulsi in Hindi, Tulsai in Sanskrit and Holy Basil in English. It is referred to as the ‘Elixir of Life’ in addition to ‘liquid yoga’. 

Tulsi grows well in the Indian subcontinent. It is a bushy shrub with lavender colored flowers and red-brown colored nuts that grows to a height of about 18 inches. There are three main sub-types of tulsi:

  • Ocimum tenuiflorum Rama or Sri Tulsi (green leaves)
  • Ocimum tenuiflorum Krishna or Shayma Tulsi (purple leaves)
  • Ocimum gratissimum or Vana (dark green leaves)

Tulsi has been a key component of Ayurvedic or Indian traditional medicine for over 3000 years and is considered to be an adaptogen. The leaves, roots, stems, and juice are all used therapeutically.

Not only is Tulsi a powerful biochemist and adaptogen, but it is also a sacred plant and aromatic culinary herb.

We will look at each of these roles in more detail.

Medical

Holy Basil contains:

  • flavonoids (orientin and vicenin) essential oils (eugenol, euginal, carvacol, linalool, limatrol, nerol, and camphor)
  • Vitamins A and C
  • Minerals (calcium, zinc, phosphorus, iron)
  • Saponins
  • Triterpenids
  • Tanins (pattanyak)
  • Eugenol (1-hydroxy-2-methoxy-4-allylbenzene) is the key bioactive in Tulsi.

From a western medical perspective, Tulsi is promoted for a wide range of complaints including bronchitis, arthritis, infertility, cancer, diabetes, heart disease and skin problems (2).

Culinary

Tulsi has a distinctive peppery taste and is used with other herbs an spices in a wide range of soups, stews, curries, cheeses, oils, jellies and drinks. Tulsi is related to but not the same as sweet basil. Sweet basil is the type of basil that is commonly sold in food stores outside of India.

I noticed that many blogs write about the benefits of both Tulsi and sweet basil without differentiating between the two. In this article, we will just deal with Tulsi and not sweet basil I would hate to think that someone read this and mistakenly thought that sweet basil would give them some health benefit that really belongs to Tulsi.

Tulsi is the key ingredient in the popular Thai dish, phat kraphao.

In India, it is also used to make sherbet.

Leaves can be used to make tea which has been described as ‘liquid yoga’.

Spiritual

As the name would suggest, Tulsi has spiritual importance. According to Hindu mythology, Holy Basil is an incarnation of the Goddess Tulsi and offers divine protection (3).

Tulsi is used in Hindu shrines and translates roughly into ‘the incomparable one’ in Hindi. It is common practice for Indian families to keep a Tulsi plant in their homes

The stalk of the Tulsi plant is often used for prayer beads such as rosary beads or malas.

Is There Any Research?

There are only 427 publications and just 11 clinical trials on Holy Basil (Ocimum sanctum). By contrast, there are over 5000 articles and 700 clinical trials on yoga.

Does It Protect Against Cancer?

A 2013 review summarized the data on Tulsi in cancer prevention and treatment (4).

The big bottom line is that a range of pre-clinical studies show that Tulsi has antioxidant and gene-altering effects in addition to an ability to prevent the growth of blood vessels and even induce cell death.

All very promising as an anti-cancer agent. However, this is all pre-clinical or non-human data and we cannot extrapolate to humans

There are a number of studies that show that Tulsi can protect against radiation damage (5). Again this is all based on data from our four legged long tailed friends.

That being said, I would not ignore this data at this time. A very wise healer once told me that the level of data needed is directly proportional to the ability to cause harm.

If I found myself in the middle of a radiation leak I would happily eat Tulsi. But I would caution people who are undergoing radiation therapy to avoid Tulsi as the entire point of radiation therapy is to kill cells.

Bottom Line

There is no evidence in humans that Holy Basil can prevent or treat cancer.

Does It Help Control Diabetes?

The only human clinical trial on this subject dates back to 1996 (6). This was a randomized, placebo-controlled, crossover single blind trial in people with non-insulin dependent diabetes.

Significant decreases of 17.6% and 7.3% in the levels of fasting and postprandial blood glucose were noted in the study and were accompanied by reductions in urinary glucose levels.

This is very encouraging data. I find it odd that no follow-up clinical trials have been done in the intervening twenty years.

Bottom Line

There is one study from over 20 years ago that shows that Holy Basil can help with blood sugar control in people with non-insulin dependent diabetes. Just to clarify, this cannot and should not be extrapolated to people with insulin dependent diabetes which is a totally different clinical entity.

Does It Improve Digestion?

There are no clinical trials on Holy Basil for digestive issues.

Ocimum gratissimum or African Basil is used in Nigeria to treat inflammatory bowel disease (7).

Ocimum gratissum has also been shown to reduce colonic inflammation in a rat model of inflammatory bowel disease.

However, while this is a member of the Lamiaceae family it is not actually Holy Basil and as such does not count.

Ocimum selloi has been shown to have an antispasmodic effect in guinea-pig ileum which is thought to be due to the blockade of calcium channels in smooth muscle (8). We have the same problem here. Related species but not our focus.

Bottom Line

Holy Basil is unproven as a digestive aid at this point in time.

Does It Treat Infections?

There is one human clinical study to look at here. The study looked at Tulsi and oral hygiene (9).

Tulsi essential oil toothpaste was compared with a triple antibiotic paste (ciprofloxacin, minocycline, and metronidazole) in a head to head study in 40 children over 3 days. There are two ways of looking at the results of this study.

If we compare bacterial counts before and after Tulsi oil, we find statistically significant reductions in bacterial cell count. If we compare Tulsi to the triple antibiotic paste, we find that the antibiotic paste outperforms Tulsi.

The authors point out that Tulsi may be less effective than an antibiotic paste but that it does work and may have fewer side effects in terms of the development of antibiotic resistance. This may be the case but it is just speculation at this time.

An ethnobotanical review found that Tulsi is used in Indian medicine to treat malaria (10). The efficacy of this traditional practice is not borne out by any clinical data.

Veterinary scientists found that Ocimum extract could reduce bacterial cell count, white cell count and inflammatory activity in cows with sub-clinical mastitis (11).

Bottom Line

There is no clinical evidence to support Holy Basil as a useful anti-infective apart from a single (not too convincing) study on oral health.

Does Basil Fight Inflammation or Boost Immunity?

Having written a number of these articles, I can’t help but notice that questions about any herb or supplement and inflammation/immunity are really unsatisfactory. Tulsi is no exception. We have a mish-mash of what could best be described as stand-alone silo studies that don’t really help us a lot.

Here are some examples.

Traditional practices suggest that Tulsi (when taken on an empty stomach) can improve immunity. This theory was tested in 22 volunteers who were randomized to either Tulsi 300mg or placebo for four weeks (12).

Statistically significant increases in a range of immune markers (gamma interferon, interleukin 4, natural killer cells and T-helper cells) was noted in the Tulsi arm as compared to the placebo arm. The clinical relevance of these changes is unclear as this was beyond the remit of the study.

An Ayurvedic tea containing ashwagandha, Glycyrrhiza glabra (cross link here), Zingiber officinale, Tulsi and Elettaria cardamomum) was shown to improve natural killer cell activity as compared to regular controls in two studies which were published together in 2010 (13). 

The problems here are that we cannot isolate out the contribution of Tulsi from the other herbs and we cannot say if the effects on the natural killer cells would be expected to be clinically significant.

Interesting but not really helpful.

Bottom Line

There is no clinically relevant data to support a role for Holy Basil in inflammatory or immune-based conditions.

Does it Combat Anxiety or Stress?

A total of 35 adults were given Ocimum sanctum at a dose of 500mg twice daily after meals for 60 days (14). A statistically significant decrease in anxiety, stress, and depression was noted in the study subjects.

A complex in-vivo and in-vitro study assessed the effects of Ocimum sanctum on the hypothalamic-pituitary-adrenal axis (the endocrine stress response) (15). This is a pretty good approach to measuring adrenal fatigue. The researchers used the chronic variable stress test which is a validated way of inducing stress and depression in rodents.

It involves any of the following grim strategies: food deprivation, water deprivation, restraint, forced swimming, flashing light and isolation. The administration of Ocimum resulted in increased weight and decreased immobility time as compared to a control group. A parallel laboratory based study in cells showed that Ocimum inhibited cortisol release.

Thirty days of Tulsi supplementation was shown to significantly improve reaction time and error rates as compared to placebo in a study on the effects of Tulsi on cognitive function (16).

Bottom Line

A small amount of research suggests Holy Basil may have positive effects on anxiety and may improve cognitive function but more research is needed to validate these findings.

Does It Help Fertility?

Male albino rats given 2g of Tulsi for 30 days were noted to have statistically significant decreases in sperm count and the authors of the study suggested that based on the results of the study that Tulsi should be investigated as a male contraceptive (17)

Another study confirmed this finding (18). Just 48 hours of exposure to Tulsi impacted negatively on sperm count, motility and velocity in rats. The good news is that this effect wore off within two weeks.

Tulsi exposure disturbed the cell architecture of the epididymis of male rats (19). The study involved a sexual performance test and no pregnancies were recorded in the female partners of rats.

Bottom Line

Data from animals suggests that Holy Basil has an anti-fertility effect.

Does it Promote Cardiovascular Health?

There are no clinical studies looking at Tulsi in heart health.

A range of pre-clinical studies have some cardiovascular benefits.

These benefits include reduced inflammation after myocardial infarction (heart attack) in rats (20).

Another study in rats showed that Tulsi can improve functional recovery post myocardial infarction (21).

Similar cardioprotective effects were found in a 2009 study in rats who had myocardial cell damage and death (22).

Bottom Line

There is no human clinical proof that Holy Basil has cardio-protective effects.

Does It Support Liver Health?

We have one clinical study to guide us here (23).

In this study, 30 overweight/obese individuals were given either Tulsi 250mg twice daily or placebo for 8 weeks. Statistically significant differences in BMI and plasma lipids were noted in favor of the Tulsi arm. Tulsi had no effects on liver enzymes.

Rat data showed that Tulsi alone or in combination with milk-thistle can protect against paracetamol induced liver toxicity (24).

Bottom Line

Human clinical data does not support Holy Basil as a liver protective agent.

Is It Safe?

The first and only systematic review of Holy Basil reported that 15 out of 24 studies reported no side effects and 8 did not refer to side effects (25). However the longest study was only 13 weeks long which is hardly reassuring. The paper had two authors, one of whom acts as a paid consultant to a company that manufactures and distributes Tulsi products. 

Like many herbal medicines, Tulsi can impair blood clotting and care should be taken when using Tulsi in people who are taking blood-thinning medication or aspirin. For the same reason, Tulsi should be avoided for at least two weeks prior to surgery.

There is also a potential interaction between Tulsi and the antiepileptic drug, phenobarbitone, which can result in excessive drowsiness.

As mentioned above, there are concerns that Tulsi can reduce fertility. This can be good or bad depending on your personal perspective.

Owing to the lack of data Tulsi should be avoided when breastfeeding.

Tulsi might decrease blood glucose and care should be taken in people who are taking antidiabetic medication including insulin.

Tulsi may also decrease levels of thyroid hormone and care should be taken in people with thyroid dysfunction.

Doshas are a fundamental concept in Ayurvedic medicine. There are three main doshas: vata (air), pitta (fire) and kapha (water). I mention this for a very specific reason.

Even though Tulsi is revered in Ayurvedic medicine, it is by no means considered to be a panacea. According to Ayurveda, Tulsi is Kapha reducing which means that it can aggravate Pitta symptoms in people who are considered to be overheated in Ayurvedic medicine.

Conclusion

Holy Basil is a really interesting herb. Data on its clinical efficacy are sadly lacking. The most impressive data on Tulsi supports its role as an anti-anxiety and pro-cognitive agent. This does fit well with its role as an adaptogen.

While Tulsi may not be the ‘liquid yoga’ that I had hoped for, I am too respectful of ancient wisdom and spirituality to just dismiss Tulsi at this point.

With just 11 trials to work with, this was never going to be a slam-dunk.

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