HerbalEGram: Volume 16, Issue 8, August 2019

By Anjanette DeCarlo, PhD,^a Stephen Johnson,^a,b and Denzil Phillips^c

^a Aromatic Plant Research Center

^b Sustainable Sourcing Consultant

^c Denzil Phillips International Ltd.

During the last five years, the worldwide demand for frankincense (Boswellia spp., Burseraceae) resin as a source of incense, medicine, cosmetics, and essential oil has grown substantially. Scientific interest in these materials also has expanded rapidly as more uses for these ingredients are being discovered or rediscovered. The growing gap between supply and demand in most areas of production is causing widespread concern among scientists, environmentalists, and the business community. Can more sustainable ways to produce and process this ancient and highly prized material be found?

The first International Congress on Frankincense and Medicinal Plants held in Muscat, Oman, in October 2018, drew global attention to the botanical, religious, medicinal, and cosmetic significance of these species. While experts from around the world presented valuable information to enhance understanding of these plants and their resin constituents, the congress also highlighted the many knowledge gaps and urgent need for further research.

The World Congress on Medicinal and Aromatic Plants (WOCMAP) organizing committee will host a special session at WOCMAP VI in November 2019 that is dedicated exclusively to the history, geography, botany, biochemistry, and economics of frankincense and myrrh (Commiphora spp., Burseraceae). Experts from different parts of the world will present the latest scientific findings about these plants, and a panel will discuss whether world trade in frankincense and myrrh, in its present form, is sustainable. For more information about the congress or contributing to this special session, please email denzil@denzil.com or contact the WOCMAP organizing committee at wocmap2019@gmail.com.

While frankincense is indeed a source of incense, its use is far more extensive. Frankincense is part of religious ceremonies worldwide, including in the Catholic, Greek Orthodox, Russian Orthodox, and Ethiopian Orthodox Churches, and in Judaism and Islam. It has been used traditionally in religious ceremonies for the psychoactive properties of its smoke and valued for its perceived transcendental ability to connect humans to their spiritual world. The resin is used in Ayurveda, traditional Chinese medicine, and other traditional health systems. Almost all frankincense species are used by local people in its native regions for health and hygienic purposes. Recent advances in understanding the chemistry of frankincense have revealed numerous biologically active molecules that are now being explored for use in Western medicine. Frankincense also is used in aromatherapy, as a cosmetic and fragrance ingredient, as a preservative and purifier, and for many other household applications throughout the world. 

2. Frankincense is not just from Arabia.

Only one species of frankincense, B. sacra, is known to grow on the Arabian Peninsula. While the resin from the frankincense trees of this region has been harvested for generations, the vast majority of frankincense that is traded internationally comes from India and the Horn of Africa, especially Ethiopia and Somalia, with Sudan and West Africa as emerging sources. Boswellia carteri (see next section) and B. frereana grow only in Somalia.

3. The names Boswellia carteri and B. sacra now are considered synonyms.

Boswellia carteri is an accepted synonym of B. sacra, with B. sacra now considered by botanists as the “official” name. Nevertheless, both Latin binomials still are used commonly for several reasons, not least of which is that both species tend to have unique scent and chemical profiles. Boswellia carteri is used to refer to the populations of B. sacra growing in Somalia, while B. sacra is used to refer to the Arabian populations.

4. Frankincense essential oil does not contain boswellic acids.

Boswellic acids are non-volatile pentacyclic triterpenes, meaning that they are not present in essential oil. Extracts, using solvents such as carbon dioxide or hexane, frequently contain boswellic acids, but essential oil does not contain any of these larger molecules.

5. Frankincense resin and essential oil are not single, homogenous products.

Frankincense from different species and locations is hugely diverse in both chemistry and aroma profiles. For example, B. papyrifera essential oil is dominated by octyl acetate and octanol; B. serrata essential oil is dominated by α-thujene; B. sacra and B. carteri essential oils are dominated by α-pinene (although some B. sacra and B. carteri oils are dominated by limonene); and the essential oil of the recently discovered B. occulta is composed primarily of methoxydecane and methoxyoctane, which give it a unique fatty, citrusy note. Boswellia dalzielii and B. serrata resins have relatively high levels of boswellic acids, which make them ideal for extracts. Boswellia frereana resin is considered the best Boswellia resin to chew due to its mild flavor, in contrast to the relatively bitter resins of B. sacra and B. papyrifera.  

6. Frankincense essential oil has not been clinically proven to treat cancer.

No clinical evidence has yet been found to support the use of frankincense essential oil for the treatment of cancer. Boswellic acids have exhibited anti-tumor properties in vivo and in vitro, but, as mentioned previously, frankincense essential oil does not contain boswellic acids. Furthermore, despite seemingly endless claims for the health benefits of frankincense essential oil — from depression to infertility — there have been no well-structured human clinical trials to support these claims, as far as is known.

7. The most expensive frankincense in the world is not Boswellia sacra or B. carteri.

The most expensive frankincense in the world in fact comes from B. frereana. Widely considered to be the “King of Frankincense,” it is known to be found only in a narrow geographical belt in northern Somalia (Somaliland and Puntland). This species is known for its large, aromatic resin deposits, commonly called “tears,” which are known as musha’ad and can be up to 30 cm long. These tears sell for up to $400 per kg and are used for display purposes and as chewing gum. The lower grades are used as incense in the Coptic Church and sometimes distilled into essential oil.

8. Frankincense is under threat in many parts of the world.

Many of the places frankincense trees grow are in insecure areas where people live in extreme poverty. While an overall independent assessment remains to be done, strong evidence suggests that Boswellia populations are suffering significant decline due to complex interdependent factors, including fire, land conversion, unclear ownership, grazing animals, and over-tapping due to increased global demand, given a lack of additional income streams for local people. A recent paper published in Nature Sustainability,¹ which draws on decades of study in Ethiopia, suggests that without dramatic changes in stewardship and harvesting practices, in some areas, the trees may be extinct within 20-30 years.

9. Boswellia can be cultivated.

Most species of Boswellia are in fact relatively easy to cultivate and will grow readily from cuttings or seedlings. Both government and private-sector nurseries exist in Oman and, while investment in commercial frankincense cultivation has been surprisingly limited, modern non-commercial drip-irrigated frankincense plantations currently are found in both Oman and the United States. Local plantation efforts also are starting in the Somaliland region of Somalia.

10. Organic certification may not imply sustainable or high-quality resin.

Organic agricultural certification does not guarantee the purity or sustainability of frankincense. Many commercial organically labeled B. carteri essential oil products recently were shown to contain oils from a mix of species, including B. occulta. Organic certification simply means that a reputable third-party has certified that artificial fertilizers and pesticides were not used in cultivation and that synthetic chemicals were not applied during the processing of the resin.

Reference

1. Bongers F, Groenendijk P, Bekele T, et al. Frankincense in peril. Nature Sustainability. 2019;2:602-610.