Frankincense

Frankincense (Boswellia spp.): A Comprehensive Reference

1. Identity and Botanical Classification

1.1 Botanical Name and Family

Frankincense is an aromatic resin obtained from a deep longitudinal slit in the trunk of the Boswellia plant, belonging to the family Burseraceae. The genus Boswellia belongs to the family Burseraceae and comprises 20–25 species of trees and shrubs widely distributed in dry areas of northeast Africa, Arabia, and India. The substance is also commonly referred to by its Latin trade name olibanum.

Some well-known species within the genus include Boswellia sacra (commonly known as Omani frankincense), Boswellia serrata (Indian frankincense), and Boswellia carteri (African frankincense). Among the various species, only a few are traded in significant amounts: B. sacra, B. carteri, B. frereana, B. papyrifera, and B. serrata. The taxonomy of Boswellia is complex, and distinguishing between species can be challenging due to their morphological similarities.

1.2 Natural Source and Harvesting

The aromatic oleo-gum-resin extracted from B. sacra, known as frankincense or olibanum, is used as a home remedy, especially in Middle East countries. Frankincense is harvested by making shallow incisions into the tree trunk. When the bark is cut, the aromatic balsam, or gum resin, oozes out and is used for medicinal purposes. The semi-solid resin is typically harvested each summer and fall and is collected in bamboo baskets, where it remains for approximately one month, during which the fluid is drained out.

The extract is composed of 30–60% resin, 5–10% essential oils and the residual matter of polysaccharides (substances that comprise many sugar molecules linked together).

1.3 Common Names and Synonyms

Boswellia serrata is also known by the names Indian frankincense, Indian olibanum, Salai guggul, and Sallaki. The Sanskrit name Shallaki appears across multiple ancient texts with remarkable consistency, though the plant is also referenced as Sallaki, Gajabhaksha, and Kundurukkam in South Indian traditions.

1.4 Common Forms and Preparations

Frankincense is available and used in several distinct forms:

• Crude oleo-gum-resin ("tears"): The aromatic oleo-gum-resin is used as a home remedy, especially in Middle East countries.
• Standardized oral extracts: Many commercial products are standardized to contain 10–15 µg/mL AKBA.
• Essential oil: Frankincense oil is extracted by the hydro-distillation or steam distillation of aromatic oleo-gum resin produced by the trees of the Boswellia genus.
• Phospholipid-complexed / enhanced-bioavailability preparations: Pharmacokinetic studies have shown low bioavailability of boswellic acids including KBA and AKBA. Phospholipid complexation enhances the bioavailability of boswellic acids, which led to the development of formulations such as solid lipid Boswellia serrata particles.
• Incense/aromatherapy: The oleo-gum resin has been used in traditional medicine, cultural, and religious ceremonies since ancient times, but now the essential oil derived from these resins has become popular in perfumery and aromatherapy.

2. Traditional and Historical Use

2.1 Ancient Egypt and the Near East

Frankincense is a fragrant resin obtained from the dried sap of Boswellia trees and has been valued for its aromatic and medicinal properties for thousands of years. Historically, it has played a significant role in religious rituals across various cultures, including ancient Assyria, Babylon, and within the Christian tradition. The resin's scent was used in ancient times for various health remedies, cosmetics, and even as a part of embalming processes in Egypt.

Frankincense was used by the ancient Egyptians in their religious rites. It constituted part of the Jewish incense of the sanctuary and is frequently mentioned in the Pentateuch. In Christian tradition, frankincense was one of the three gifts offered by the Magi to the infant Jesus; it is often understood as symbolizing his priestly role.

2.2 Classical Antiquity and Medieval Periods

Pliny the Elder described the characteristics of good-quality frankincense and mentioned it as an antidote to hemlock poisoning. The Iranian physician Avicenna recommended it for a wide range of bodily ailments. In China and elsewhere in the East, it has long been used as both an internal and external remedy.

2.3 Ayurvedic Tradition (India)

Records of Boswellia serrata date back over two millennia. Sanskrit texts like the Charaka Samhita and Sushruta Samhita praise Shallaki for easing Vata imbalances, particularly Vata-related joint pains. Indian healers ground the resin into a powder or blended it with ghee for oleation therapies known as sneha. In northern Himalayan traditions, the resin was often consumed in milk decoctions (Kshira Paka)—a preparation method that demonstrates pharmacological sophistication, since milk's fat content would enhance the bioavailability of the resin's lipophilic boswellic acid constituents.

Stripping off the paper-thin bark of Boswellia trees reveals a gummy oleoresin, extracts of which have been used in Ayurvedic medicine for their anti-inflammatory, antiseptic, astringent, and stimulant activity to treat inflammatory conditions and gastrointestinal complaints.

2.4 Traditional Chinese Medicine and Other Traditions

The properties of Boswellia plants have been exploited for millennia in the traditional medicines of Africa, China, and especially in Indian Ayurveda. Traditional healing systems such as Ayurveda and Traditional Chinese Medicine have utilized frankincense for its anti-inflammatory, analgesic, and antimicrobial properties.

2.5 Traditional Medicinal Uses Across Cultures

This traditional medicine of the East is believed to have anti-inflammatory, expectorant, antiseptic, and even anxiolytic and anti-neurotic effects. The oleoresin gum from B. serrata has traditionally been used for its anti-inflammatory effects in conditions such as asthma, osteoarthritis, rheumatoid arthritis, colitis, and irritable bowel syndrome. It has also been used for the management of diabetes, urinary conditions, dermatological ailments, and renal impairment.

3. Key Chemical Constituents

3.1 Resin Fraction: Boswellic Acids

Frankincense is a rich resource for bioactive compounds, especially boswellic acids and derivatives. The extract is composed of 30–60% resin, 5–10% essential oils, and the residual matter of polysaccharides. The chemical constituents of the 30–60% resin fraction include beta boswellic acids, and mono-, di-, and triterpenes, which have been scientifically examined for their anti-inflammatory potential.

The primary boswellic acids identified in the literature include:

• β-Boswellic acid (β-BA)
• 11-keto-β-boswellic acid (KBA)
• 3-O-Acetyl-11-keto-β-boswellic acid (AKBA) — considered the most pharmacologically potent
• α-Boswellic acid (α-BA)
• 3-Acetyl-β-boswellic acid (ABBA)

The highest biological activity among terpenes is characteristic of 11-keto-β-acetyl-beta-boswellic acid, acetyl-11-keto-β-boswellic acid, and acetyl-α-boswellic acid.

3.2 Volatile Oil Fraction

The main component of frankincense is oil (60%). It contains mono- (13%) and diterpenes (40%) as well as ethyl acetate (21.4%), octyl acetate (13.4%), and methylanisole (7.6%). Altogether, more than 340 volatiles in Boswellia have been reported in the literature. A broad diversity has been found in the qualitative and quantitative composition of the volatiles with respect to different varieties of Boswellia. The presence of high amounts of α-pinene in Omani frankincense oils can be considered a chemotaxonomical marker that confirms the botanical and geographical source of the resins.

4. Mechanisms of Action

4.1 Inhibition of 5-Lipoxygenase (5-LOX)

Boswellic acids (BAs) act as specific non-redox inhibitors of 5-lipoxygenase (5-LOX) product formation. They exert their effects either by directly interacting with the 5-LOX enzyme or by blocking its translocation. Among the BAs, AKBA demonstrates the most potent inhibitory activity against 5-LOX products, with a reported IC50 value of 1.5 μM in human neutrophils (non-redox, non-competitive; in vitro). It directly inhibits 5-LOX by a selective, enzyme-directed, non-redox, and non-competitive mechanism.

The inhibition by acetyl-11-keto-beta-boswellic acid was not due to nonspecific lipophilic interactions, because lipophilic four-ring compounds (cholesterol, cortisone, and testosterone) neither inhibited the activity of the 5-lipoxygenase nor antagonized the inhibitory action of AKBA. Therefore, it was concluded that AKBA acts directly on the 5-lipoxygenase enzyme at a selective site for pentacyclic triterpenes that is different from the arachidonate substrate binding site.

Both AKBA and KBA demonstrated strong inhibition of 5-LOX across all systems, while α-boswellic acid (α-BA) exhibited greater inhibitory activity than β-boswellic acid (β-BA).

4.2 Inhibition of NF-κB and Cytokine Suppression

Multiple biological effects of boswellic acids have been identified, such as inhibition of 5-lipoxygenase, leukocyte elastase, nuclear factor kappa-B (NF-κB), and cyclooxygenase. AKBA shows chemo-preventive characteristics capable of targeting principal oncogenic proteins, including 5-lipoxygenase and nuclear factor-kappa B.

4.3 Inhibition of Leukocyte Elastase and Glycosaminoglycan Degradation

Boswellia extracts reduce inflammatory conditions in the course of rheumatism by inhibiting leukocyte elastase and degrading glycosaminoglycans. Boswellia preparations inhibit 5-lipoxygenase and prevent the release of leukotrienes, thus having an anti-inflammatory effect in ulcerative colitis, irritable bowel syndrome, bronchitis, and sinusitis.

4.4 Effects on MAPK Pathways

The mechanisms of activity of BAs comprise a variety of targets, including the enzymes of angiogenesis and others such as topoisomerases, 5-lipoxygenase (5-LO), cytochrome P450, and mitogen-activated protein kinase (MAPK, especially p38), which are either promoted or inhibited by BAs.

4.5 Inhibition of Topoisomerases and Apoptosis

AKBA and KBA are assessed by active inhibition of topoisomerase I and IIa, which restricts the growth of cells. Boswellic acids have also been shown to stimulate apoptosis by a mechanism depending on caspase-8 but independent of Fas/Fas ligand pathways.

5. Scientific Evidence by Area of Use

5.1 Osteoarthritis

Osteoarthritis, particularly of the knee, is the condition with the most substantial body of clinical evidence for Boswellia serrata extracts.

A systematic review and network meta-analysis of 39 randomized controlled trials found that Boswellia significantly improved pain, stiffness, and function in patients with knee osteoarthritis.

A systematic review and meta-analysis of 13 randomized controlled clinical studies involving 2,035 patient outcomes found a significant beneficial effect of using Boswellia oleogum resin phytoextracts on symptoms of knee osteoarthritis compared with placebo, with the finding being particularly important for people experiencing adverse effects from the use of NSAIDs.

A double-blind, placebo-controlled human trial evaluated the safety and efficacy of a standardized oral supplementation of Boswellin®, a novel extract of Boswellia serrata (BSE) containing AKBBA with β-boswellic acid (BBA). A total of 48 patients with osteoarthritis (OA) of the knee were randomized and allocated to the BSE and placebo groups for intervention. Patients were administered BSE or placebo for a period of 120 days. The trial results revealed that BSE treatment significantly improved the physical function of the patients by reducing pain and stiffness compared with placebo. Radiographic assessments showed improved knee joint gap and reduced osteophytes confirming the efficacy of BSE treatment. BSE also significantly reduced the serum levels of high-sensitive C-reactive protein (hs-CRP). No serious adverse events were reported.

A randomized, double-blind, placebo-controlled trial evaluated the efficacy and safety of Boswellia serrata extract (BOSMAX®) in participants with non/mild OA. A total of 150 adults aged 40–75 were randomized to receive either BOSMAX® or a placebo daily for 90 days. Primary outcome measures included WOMAC scores, visual analog scale (VAS) for pain, and Lequesne Functional Index; secondary endpoints were SF-36 scores, TNF-α, and hs-CRP. Significant improvements were observed in the BOSMAX® group compared with the placebo. The mean total WOMAC scores decreased significantly at days 30, 60, and 90. Lequesne Index scores improved progressively. TNF-α and hs-CRP levels decreased significantly at day 90.

Several studies have shown taking boswellia orally may help reduce inflammation and pain associated with osteoarthritis, but larger, higher quality studies are needed. Overall, the evidence for osteoarthritis is the most clinically developed of any indication, though the NCCIH notes that study quality remains variable.

5.2 Asthma and Respiratory Conditions

A few small studies suggest that taking boswellia orally may reduce asthma symptoms. An RCT on asthma patients showed Boswellia at a dose of 300 mg three times per day improved dyspnea, rhonchi, number of asthma attacks, and spirometry readings in 70% of subjects compared with only 27% of controls receiving placebo. A few small studies suggest that taking boswellia orally may reduce asthma symptoms. The evidence is promising but limited by small sample sizes and the need for independent replication.

5.3 Inflammatory Bowel Disease (IBD)

In ulcerative colitis, Boswellia serrata gum resin and plantago ovata seeds were as effective as mesalazine in certain comparative trials.

In a meta-analysis, the relative risk (RR) of clinical remission was significant for Boswellia serrata (RR 2.34; 95% CI: 1.02–6.07). Sub-analyses demonstrated that induction of clinical remission was obtained for Boswellia serrata and Artemisia absinthium. Induction of adverse events by none of the plants was significant compared with placebo.

However, not all trials have been positive. The aim of one large study was to evaluate the efficacy and safety of long-term therapy with a new Boswellia serrata extract (Boswelan) in maintaining remission in patients with Crohn's disease. In 22 German centers, a double-blind, placebo-controlled, randomized, parallel study was performed with 108 outpatients with CD in clinical remission. Patients were randomized to Boswelan (3×2 capsules/day; 400 mg each) or placebo for 52 weeks. The trial confirmed good tolerability of the Boswelan extract in long-term treatment of CD; however, superiority versus placebo in maintenance therapy of remission could not be demonstrated.

Overall, the evidence for IBD is mixed: some positive results in ulcerative colitis, but B. serrata failed to demonstrate superiority over placebo for maintenance of remission in Crohn's disease in the largest dedicated trial.

5.4 Cerebral Edema and Brain Tumors

In 2002, the European Medicines Agency classified BSE as an "orphan drug" for the treatment of peritumoral brain edema.

A prospective, randomized, placebo-controlled, double-blind pilot trial in 40 patients receiving radiation therapy for brain tumors showed that Boswellia serrata significantly reduced cerebral edema.

Streffer et al. provided the first prospective evidence on boswellic acid use for cerebral edema management. Twelve patients (11 with glioma and 1 with brain metastases) with progressive cerebral edema were treated with 3 × 1,200 mg of boswellic acid (as an H15 preparation) per day. Patients were either not taking corticosteroids or their dose had remained unaltered during the last month. Edema was successfully reduced in 2/7 (29%) patients with tumor progression-related edema and in 3/5 (60%) with treatment-related edema. In one quarter of patients, corticosteroids were reduced or completely withdrawn. No side effects related to boswellic acid intake were reported.

Early clinical evidence suggests beneficial effects of boswellic acid in the context of cerebral edema during and following radiotherapy, rendering it an attractive option to avoid prolonged corticosteroid intake in symptomatic patients; however, this is largely based on anecdotal evidence. Larger and better-controlled trials remain needed.

5.5 Rheumatoid Arthritis

Studies have been related to the treatment of asthma, rheumatoid arthritis, Crohn's disease, collagenous colitis, and osteoarthritis. The topical use of boswellia (frankincense) for osteoarthritis, rheumatoid arthritis, and other health conditions has been studied, but there isn't enough evidence to show that it is an effective treatment. Evidence for rheumatoid arthritis remains weaker than for osteoarthritis.

5.6 Anticancer Properties (Preclinical and Limited Clinical)

Boswellic acids have an antiproliferative effect on tumors. They inhibit proliferation of tumor cells of the leukemia and glioblastoma subset. Several scientific studies have shown Boswellia's pentacyclic triterpenes as one of the most promising anti-cancer agents in preclinical work. In the last decade, boswellic acids were shown to also have effects against brain tumors, hepatitis, and inflammatory bowel diseases in preclinical models.

No complementary approach has been shown to cure cancer or cause it to go into remission. The anticancer evidence for frankincense remains primarily preclinical (cell lines and animal models), with the only clinical data pertaining to the management of radiation-induced cerebral edema rather than direct tumor cytotoxicity in humans.

5.7 Overall Strength of Evidence — Regulatory Assessment

Of 47 potentially relevant studies in one systematic review, seven met all inclusion criteria. The evidence for the effectiveness of B. serrata extracts is encouraging but not compelling. There have been several studies on the potential health benefits and safety of using boswellia, but most of these are small and of low quality. There is not enough high-quality evidence to determine whether boswellia is useful for any health condition. The NCCIH assessment reflects the current consensus: the most consistent positive findings are for knee osteoarthritis, with weaker or mixed evidence for other conditions.

6. Body Systems and Health Areas

Based on the published literature, frankincense/Boswellia preparations have been studied in relation to the following body systems and health areas:

• Musculoskeletal system: Osteoarthritis (especially knee), rheumatoid arthritis, joint pain, and stiffness
• Gastrointestinal system: Ulcerative colitis, Crohn's disease, irritable bowel syndrome, collagenous colitis
• Respiratory system: Bronchial asthma, bronchitis, sinusitis
• Central nervous system / oncology: Peritumoral and radiation-induced cerebral edema, glioblastoma-associated edema
• Immune system: Modulation of inflammatory cytokines, leukotriene production, and NF-κB signaling
• Dermatology / topical use: In modern times, frankincense is increasingly utilized in aromatherapy and as an ingredient in cosmetics due to its purported benefits for skin health and relaxation.

7. Dosage Forms and Dosages Reported in Studies

7.1 Oral Supplementation

Boswellia serrata extract in doses up to 1,000 mg daily has been safely used in several clinical trials lasting up to 6 months. It has also been used with apparent safety at a dose of 2,400 mg for up to one month.

Boswellia serrata has most often been used by adults in doses of 100–250 mg by mouth daily, for up to 6 months.

Condition-specific dosages reported in trials include:

• Osteoarthritis (knee), pilot RCT (120 days): A standardized oral supplementation of Boswellin® containing AKBBA and BBA was administered to 48 patients for 120 days.
• Osteoarthritis (knee), RCT (90 days): A total of 150 adults were randomized to receive either BOSMAX® or a placebo daily for 90 days.
• Asthma: 300 to 400 mg of an extract (containing 60% boswellic acids) 3 times daily. An RCT used a dose of 300 mg three times per day.
• Crohn's disease maintenance: Patients were randomized to Boswelan (3×2 capsules/day; 400 mg each) or placebo for 52 weeks.
• Cerebral edema (radiation necrosis): Patients were recommended a target Boswellia dose of 4,050 to 4,500 mg daily in divided doses.
• Cerebral edema (H15 preparation): Twelve patients were treated with 3 × 1,200 mg of boswellic acid (as an H15 preparation) per day.

In Western countries, the advent of synthetic drugs obscured the pharmaceutical use of Boswellia, until it was reported that an ethanolic extract exerts anti-inflammatory and antiarthritic effects. Standardized extracts (e.g., H15, AKBA-enriched formulations, phospholipid complexes) are now the predominant research-grade and commercial forms.

8. Safety Considerations and Interactions

8.1 General Tolerability

Boswellia serrata extract has not been linked to serum enzyme elevations during therapy, although there have been few prospective studies in humans that have reported on its effects on laboratory test results in any detail. In small trials, Boswellia extracts have appeared to be well tolerated with only minor and few adverse effects which have been similar in frequency among persons receiving placebo.

When taken by mouth, Boswellia serrata is likely safe for most adults. Boswellia serrata extract has been used safely in doses up to 1,000 mg daily for up to 6 months. It usually doesn't cause major side effects. But some people have reported stomach pain, nausea, diarrhea, headache, heartburn, and itching.

A review of 47 clinical trials using Boswellia to treat asthma, rheumatoid arthritis, Crohn's disease, osteoarthritis, and collagenous colitis reported that no serious safety issues were noted.

8.2 Hepatotoxicity

Boswellia extract has not been convincingly linked to published instances of clinically apparent liver injury. Boswellia is often included in multi-ingredient dietary supplements, some of which have been implicated in liver injury, but a specific contribution from Boswellia to the injury could not be established. The LiverTox likelihood score is E (unlikely cause of clinically apparent liver injury).

8.3 Pregnancy and Lactation

Boswellia may increase menstrual flow (emmenagogue) and induce miscarriage (abortifacient). Use of Boswellia should be avoided during pregnancy. Boswellia may cause miscarriage. There is no information available about the use of Boswellia while breastfeeding.

8.4 Drug Interactions — Cytochrome P450 Enzymes

Upon liquid chromatography–mass spectrometry analysis, frankincense derived from B. serrata demonstrated inhibition of CYP1A2, 2C8, 2C9, 2C19, 2D6, and 3A4. Therefore, caution is warranted when using B. serrata with medications that are substrates for these isoenzymes.

8.5 Drug Interactions — P-Glycoprotein

Data suggest that B. serrata extract and the major boswellic acids may be potent inhibitors of P-glycoprotein (P-gp) via modulation of transport activity at the GI level, but not at the blood-brain barrier.

8.6 Bioavailability Limitations

Pharmacokinetic studies have shown low oral bioavailability of boswellic acids, including KBA and AKBA. A micellar extract significantly enhanced oral bioavailability of boswellic and lupeolic acids from Boswellia serrata compared with a native extract in healthy volunteers (N=20); however, the anti-inflammatory capacities of the extracts did not significantly differ. This means that claims about equivalent dosing across different formulation types require careful scrutiny.

8.7 Sustainability and Supply Considerations

Rising demand for frankincense has raised concerns about sustainability, as excessive harvesting practices threaten the trees and their habitats. This is not a clinical safety issue for individual consumers, but it bears on the consistency and authenticity of commercially available materials.

References

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