Introduction

There are over one million websites out there on frankincense. So says a 2008 review on frankincense in the British Journal of Medicine (1). Reader beware. This review points out that the majority of these websites on frankincense ‘fail to offer reliable information on its medicinal uses’.

It has been ten years since that review was published.

As there is growing interest in this traditional medicine of the East which is believed to have anti-inflammatory, antiseptic, anxiolytic and healing effects on coughs, it seems like a good time to provide an updated, reliable, evidence based review on frankincense .

What Is Frankincense Oil?

The word ‘frankincense’ comes from the French term for ‘pure incense’. Frankincense ((乳香 Rǔ Xiāng, olibanum) is resin from the trunks of large sized branching trees of the Burseraceae family (Genus Boswellia). The trees produce high quality resin for just three years and then need time to rest. I wish that I could be productive for three years straight before needing a rest.

Frankincense is produced by four species of the Boswellia tree which come from different regions in the world:

  • Boswellia serrata from India,
  • Boswellia carterii from East Africa and China,
  • Boswellia frereana from Northeast Africa (Somalia) and
  • Boswellia sacra from the Middle East.

Nowadays, the main exporters of frankincense worldwide are Somalia, Oman and Yemen.

Frankincense is known as a traditional medicine of the east and is used for pain, inflammation, arthritis, asthma, cancer and memory (2). In the Indian Ayurvedic traditional system of medicine, it is known as Salai guggal (3).

It has a pleasant and distinctive smell and is very popular in the cosmeceutical industry. It is also commonly used in religious and cultural ceremonies.

The main component of frankincense is oil (60%). It contains mono and diterpenes, ethyl acetate, octyl acetate and methylanisole. The main biologically active terpenes is boswellic acid (C32H52O4). Frankincense is generally composed of 5–9% essential oil, 65–85% alcohol-soluble resin and the remaining is water-soluble gums (4).

Frankincense resin contains monoterpenes, diterpenes, triterpenes, tetracyclic triterpenic acids and four major pentacyclic triterpenic acids i.e. β-boswellic acid, acetyl-β-boswellic acid, 11-keto-β-boswellic acid and acetyl-11-keto-β-boswellic acid.

In the story of the birth of Jesus, the three wise men brought gifts of gold, frankincense and myrrh. It is not uncommon for people to mix up myrrh and frankincense. Perhaps this can be attributed to the fact that they both feature in one of the key stories in the Christian tradition. Perhaps this is due to the fact that they are both resins that come from the Burseraceae family of trees.

However, they come from different trees (Boswellia and Commiphora) and have different constituents (5). In Traditional Chinese Medicine, frankincense and myrrh are often co-prescribed.

The connection with Christianity does not end there. Frankincense is used as incense in Christian burial services (6). There are many interpretations of the function of frankincense at funerals including reducing the smell of death, protection against infection or symbolizing resurrection.

Of note, frankincense is sometimes diluted with other compounds to reduce costs and there are some concerns about the overall safety of burning incense (7). As we will see later there is another possible benefit of incense in funereal rites.

There are 271 boswellia products for sale on Amazon including capsules, tablets and oils. A 1200 mg tablet of frankincense costs on average $0.34.

Is There Any Research?

There are 612 articles and 43 clinical trial publications on frankincense.

To put this into context, there are 2232 publications and 228 clinical trials on lavender.

Does Frankincense Oil Reduce Stress Reactions and Negative Emotions?

Stress-Despair-BurdenA study in mice showed that frankincense binds to the transient receptor potential vanilloid (TRPV) 3 and produces an anxiolytic effect in mice (8).

In fact, the role of Boswellia as an anxiolytic dates back to antiquity.

In the Talmud, Boswellia was given to prisoners on death row to ‘“benumb the senses” back in 300 CE or AD (9).

In Ethiopia, Boswellia is believed to have a tranquillizing effect (10).

Perhaps, this is also why frankincense is used in funeral ceremonies?

Bottom Line

There is no clinical trial to support a role for Boswellia in anxiety. On the other hand, there is a historical precedent supporting its use and a small pre-clinical trial of biological plausibility.

Does Frankincense Treat Cancer?

Dry sap samples of frankincense and myrrh from Ethiopia were tested in a tumor cell line (11). It has to be said that there are lots of different types of tumor cells so at the outset we have to acknowledge the limitations of this study. Not to even mention the fact that it is an in vitro and not in vivo study.

The study showed that myrrh had more potent anti-cancer activity than frankincense and that there was no evidence of synergy between the oils (which is interesting considering the fact that they are often co-prescribed).

Bottom Line

There is essentially no helpful data on frankincense in cancer.

Does Frankincense Oil Kill Harmful Germs and Bacteria?

The data on infectious diseases is a little more promising than the cancer data.

South African investigators studied the effects of a combination of frankincense and myrrh in a range of bacteria in a laboratory setting (12 ). They studied Pseudomonas, Bacillus and a fungus called cryptococcus. They found that the combination of frankincense plus myrrh was synergistic or additive but not antagonistic.

From a microbiological perspective, synergy refers to enhanced bacterial killing when two agents are used together as opposed to the sum of the individual contribution each agent would make. Additive refers to the total bacterial killing equalling the sum of the contribution from each oil.

Antagonism refers to a situation whereby the oils would interfere with each others killing activity and when the total bacterial killing would be less than might be expected from the sum of the two oils. The study showed enhanced activity (a mixture of synergy and additive effects) when frankincense was used with myrrh. This makes sense.

The ancients may just have somehow figured this out which explains why they co-prescribed these two oils. Before we dismiss the knowledge of the ancients, we have to admit they did a great job with Stonehenge, the pyramids and Machu Picchu.

In another study, a total of 93 women with uncomplicated urinary tract infections were randomized to either a combination of either L-Methionine plus  Hibiscus sabdariffa and Boswellia serrata (the phytotherapy arm) or a short course of antibiotics (13).

Both groups reported a statistically significant improvement in quality of life at three months of follow-up. At six months of follow-up, there was a statistically significant difference between the groups in favor of the phytotherapy arm. Significantly more patients in the phytotherapy arm were noted to have clearance of the bacteria in their urine at six months of follow up.

This study really interests me as I am an infectious diseases physician and we are obsessed with antimicrobial stewardship to prevent (or maybe just delay) the post-antibiotic era (when we run out of antibiotics).

A very recent paper from Italy randomized 450 men with bacterial prostatitis to an active enzyme plus Boswellia plus pine or placebo for two months (14). The purpose of the enzyme was to enhance breakdown and drainage of prostatic secretions.

The study results were a little confusing as they sub-divided patients into different groups according to their type and severity of prostatitis. However, overall there was no significant difference between the groups (unless you look at the deeper sub-analysis which is always a bit suspect).

Bottom Line

Despite some preliminary data that frankincense may help with some infectious diseases, there is insufficient evidence to recommend frankincense as an anti-infective at this time. Anyway, it is entirely daft to say that anything kills germs or bacteria as there are so many different types of bacteria.

Does Frankincense Oil Prevent Signs of Aging?

old-manThe 2008 review mentioned in the introduction had the following to say about the anti-ageing effects of Boswellia –

‘it might be tempting to buy “instant youth” in the form of a B serrata product for Christmas, but sadly the evidence for this claim is nonexistent’ (1). Ouch. I am glad that I don’t have shares in frankincense creams and potions.

Even though the frankincense industry has continued to grow since then and new patents have been filed, there is not much in the line of new research. A single study from 2010 looked at the effects of Boswellia on photo-aging in a randomized, double-blind, placebo-controlled, split-face study (15).

A total of 15 women participated in the study. A split-face study design means that each woman applied the cream to one half of their face and not the other and then compared the results. The study took place over 30 days. Statistically significant improvements were noted according to a range of subjective and objective measures.

This tiny study which took part over a very short period of time can hardly be used as the basis for claims that Boswellia is a credible anit-aging agent.

I often wonder with split-face studies if the study participants get access to the trial agent after the study to balance out their appearance?

Bottom Line

Boswellia is not a credible anti-ageing cosmetic agent.

Does Frankincense Oil Improve Memory?

Boswellia is widely promoted as a memory aid. There are 18 publications relating to memory and boswellia.

Only two studies involved human subject material (the others were studies done in rats). Iranian investigators randomly allocated 80 patients with multiple sclerosis to either placebo or Boswellia supplementation for two months (16). Memory tests were performed before and after the study.

This meant that each subject acted as their own control. Boswellia showed significant improvements in visuospatial memory, but had no effect on verbal memory and information processing speed. Memory is very complex and there is more than one type of memory. Visuospatial memory deals with the spatial relationship of things to one another.

The second study used fetal human brain cells which were ‘stressed’ to produce Alzheimers like changes in the cells. Boswellia helped decreased free radical species generation and promoted proliferation of astrocytes (17).

Bottom Line

It would be hard to bank my future brain power on two small studies that don’t even represent the general ageing population. For that reason, and because memory is too important to trifle with, I am going to say that frankincense has not been proven as a memory aid.

Does Frankincense Oil Act as a Sleep Aid?

This is a big question and an important issue. Unfortunately, the answer is as yet elusive.

We only have one study to draw on here. British researchers gave out 65 aroma sticks (personal inhaler devices that contain essential oils) (18). The devices contained one of two essential oil blends (Bergamot (Citrus bergamia) and sandalwood (Santalum austrocaladonicum) or frankincense (Boswellia carterii), mandarin (Citrus reticulata) and lavender (Lavandula angustifolia)).

The study reports that people liked the aroma sticks and that they helped with sleep. Was the effect on sleep significant? Was there a difference between the two blends of oil? I can’t say. Essentially, this was an aroma stick study and not a frankincese study.

Bottom Line

There is no evidence to support a role for Boswellia in sleep.

Does Frankincense Oil Boost Immune System Function and Prevent Illness?

Researchers in Oklahoma found that frankincense induced cell death in bladder tumor cells (19).

Bottom Line

The extremely limited data that we have cannot help us to reach any conclusions on frankincense and immune function.

Does Frankincense Oil Help Balance Hormones and Improve Fertility?

It is said in the literature that Boswellia may aid fertility by affecting pituitary hormones and by affecting sperm motility.

I could not find any studies to support a role for Boswellia and it effects on the pituitary hormone axis.

Saudi investigators studied the effect of Boswellia smoke on spermatogenesis and sperm parameters in 11 male albino rats (20). The rats were exposed daily in smoking chambers to smoke emanated by burning 4 g each of either B. papyrifera or B. carterii for 48 days. The rats were then sacrificed.

The autopsies showed atrophy (wasting) of the semineferous tubules and significant decreases in sperm count, motility and speed. Not a good outcome, I think we can agree.

There is a study by Nusier that is commonly quoted and re-quoted referring to sperm motility but it is not referenced on PubMed and as such we cannot really do much with second-hand data (that would be healthy but dumb) (21).

A pretty odd study looked at the effects of Boswellia on pregnancy in diabetic rats (22).The study gives a fascinating account of how the rats became pregnant and how the pregnancies were diagnosed. I guess I never thought about how rat pregnancies were diagnosed before I read this article. Regardless, the study showed that Boswellia decreased the pregnancy rate.

Bottom Line

Frankincense has not been proven to help fertility. In fact, the available data suggests an anti-fertility effect.

Does Frankincense Oil Decrease Inflammation and Pain?

Frankincense contains four major pentacyclic triterpenic acids i.e. β-boswellic acid, acetyl-β-boswellic acid, 11-keto-β-boswellic acid and acetyl-11-keto-β-boswellic acid which can inhibit of pro-inflammatory enzymes. Out of these four boswellic acids, acetyl-11-keto-β-boswellic acid is the most potent inhibitor of 5-lipoxygenase, an enzyme responsible for inflammation (23).

Iranian investigators found that frankincense could help with gingivitis, an inflammatory condition of the gums (24). They randomized 75 female high school students to either 0.1 gram of Frankincense extract or 0.2 gram of its powder or placebo for 14 days.

The results showed that scaling and root planning in addition to Frankincense extract or powder led to statistically significant decreases in inflammatory indices in comparison to the groups without scaling or frankincense therapy.

In 2011, German investigators studied the effects of Boswellia on 108 out-patients with Crohn’s Disease (25). The patients were randomized to either Boswellia 2400 mg per day or placebo for 52 weeks. The primary aim of the study was to evaluate the effects on remission from Crohn’s Disease.

An interim analysis of 66 patients showed that 59.9% of the actively treated patients and 55.3% of the placebo group stayed in remission. Basically, there was no difference. The study was terminated early as superiority versus placebo in maintenance therapy of remission could not be demonstrated.

An older German study (1998) studied the effect of Boswellia in 40 adults with asthma (26). The study participants were randomized to either Boswellia or placebo for six weeks.

The study showed that a significantly greater number of patients in the treatment arm had improvements in indicator symptoms such as dyspnoea, wheeze and number of attacks and objective lung function tests.

The main claim to fame for frankincense in traditional medicine is its role in the management of arthritis. One study compared Boswellia to placebo in 30 patients with osteoarthritis of knee (27). This study had a cross-over design. The patients received the Boswellia/placebo as per the randomization for 8 weeks. They then had a wash-out period of 8 weeks.

Then then crossed over to the other treatment for a further 8 weeks.There were statistically significant improvements in knee pain, increased knee flexion and walking distance but no radiological improvement noted.

A 2017 study carried out in Iran evaluated the effect of E. angustifolia alone and in combination with B. thurifera compared with ibuprofen in patients with knee osteoarthritis (28). E angustifolia is also known as Russian olive. A total of 75 patients with osteoarthritis participated in this study.

All three intervention arms of the study had statistically significant benefits in terms of pain and function and there were no differences noted between the three study arms. Unfortunately, this does not tell us too much about Boswellia but it is interesting that the researchers looked at head-to-head studies with plants and non-steroidal anti-inflammatories.

Researchers from the US and India who came from the private sector and academia published a study just this year which is of interest (29). They studied a compound designated as LI73014F2 which is a novel composition prepared from extracts of Terminalia chebula fruit, Curcuma longa rhizome, and Boswellia serrata gum.

A total of 105 study participants were randomized to either placebo or LI73014F2 at a dose of 200mg or 400mg per day for 90 days. Statistically significant improvements in pain relief, physical function, and quality of life was noted in the osteoarthritis patients on L173014F2 and these benefits were noted as early as 14 days into the treatment.

I don’t mention this study because it is the very best Bowellia study but for another reason. I notice an emerging trend at both botanical conferences and in the medical literature that is worth commenting on. Traditional healing systems usually used synergistic combinations of plants or herbs.

This means that the herbs or plants acted together to give a better result than if used separately. The modern research and development pharmaceutical industry uses a reductionist approach whereby they isolate out individual molecular compounds and sell them to us separately.

Studies such as this are bringing us back to healing practices where we study combinations and not just individual compounds. I really like this approach.

Bottom Line

There is some evidence in the scientific literature that Boswellia acts as an anti-inflammatory.

Does Frankincense Oil Ease Digestion?

There are no studies looking at Boswellia and digestion.

Bottom Line

There are no studies connecting Boswellia and digestion

Is it safe?

No major safety concerns were raised in any of the clinical studies on Boswellia (25).

Due to a lack of data, it is generally recommended that Boswellia be avoided during pregnancy and breastfeeding.

No significant drug interactions have been reported for Boswellia.

Conclusions

The comprehensive 2008 review on frankincense concluded that ‘Many of the medical, quasimedical, or cosmetic claims made implicitly or explicitly for B serrata products are not supported by the available evidence’. This conclusion is still valid today, despite the ten years of additional research that we now have.

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