Photo: Boswellia sacra by Scott Zona
The B. sacra (Omani luban) tree is native to Yemen, Oman, and Somalia. It yields the best and most prized frankincense gum. The tree rarely grows taller than 20 feet. It bears whitish yellow flowers. Phytochemical analysis of the essential oil from botanically certified oleogum resin of B. sacra show that E-β-cymene and limonene make up 97.3 percent of the oil, followed by sesquiterpene E caryophyllene at 2.7 percent (Al-Harrasi and Al-Saidi, 2008). This analysis further shows a complete absence of diterpenes.
The world’s finest B. sacra frankincense comes from the Dhofar region in Oman, which lies in the Nejd valley with steep slopes of the rich soil and dense limestone. The climate is dry, hot, and xerophytic. The local Beit Kathir and al Mahra tribes control the frankincense trade, and the best trees are restricted to a small geographic region. Thus, consumers have been forced to look for alternatives. Cheaper substitutes may smell like frankincense, but they do not yield the white smoke that is typical of the pure oleoresin.
Boswellia sacra resin exudes from the stem when the bark is either naturally or artificially stripped. Tapping of the resin is done by blazing, or cutting, the tree at multiple points. The resin forms tears, which are left in situ (the place of exudation) to dry and then collected by gum collectors. The blazes must be refreshed twice annually in spring and fall to re-open the channel, similar to other resin-yielding trees. The best resin is clear white with a greenish tinge, and it is said to be reserved for the Sultan of Oman. Very little resin is exported.
The entire B. sacra frankincense production region is adversely impacted by increasing biotic pressure from increased cattle herds. A lack of forest management and protection has led to exploitation and deforestation of B. sacra trees. The International Union for Conservation of Nature has classified the species growing in Oman, Somalia, and Yemen as “near threatened” category and has declared that the trees in Oman are so heavily harvested that they no longer flower or produce seed. This has led to rapid depletion of tree stock.
Studies further indicate that the Oman stands suffer from endemism, which diminishes gene pool diversity and increases the threat of extinction. The absence of a scientific supply chain, inadequate habitat protection, and the geopolitical situation in Yemen and Somalia has further adversely impacted the habitat.
Medicinal Use of Boswellia Sacra. As previously stated, chewing frankincense gum is common in Arabian countries, especially Saudi Arabia. It is traditionally believed that gum chewing is good for oral hygiene. Studies conducted in five human females aged 25–35 found that chewing frankincense gum for five hours reduced bacterial activity.
The antibacterial, anti-inflammatory, and anticarcinogenic properties of the oleoresin have also been tested and validated in animal trials. Treatment with essential oil of frankincense enhanced cell death and decreased growth of human breast cancer and skin cancer cells, indicating possible pharmaceutical use.
Tests conducted on the fungi Aspergillus flavus and Aspergillus parasiticus reveal that the resin and oil of B. sacra reduces carcinogenic and other deleterious effects of the fungus, validating its traditional use as a food preservative. The essential oil, which is distilled from gum crystals, is used in aromatherapy and massage oils and sold under various trade formulations. It has a soothing effect on the nerves and takes four to six hours to evaporate, properties which make it a useful fixative in incense making.