Of the 20,000 terpenes found in nature and the 200 that may manifest in a particular strain of cannabis, limonene is one of the major players. This terpene sometimes constitutes up to 16 percent of the volume (by weight) of a particular sample of cannabis.
Terpenes are the highly aromatic molecules produced by thousands of plants in nature, typically as a defense mechanism against predators and pests. The human body, as it evolved alongside plants, developed specialized receptors in its brain, nervous system, and immune system that are compatible with not only internally produced enzymes, proteins, and other life-giving chemicals, but also phytochemicals from the plant world—including terpenes from cannabis.
The Details of Limonene
Limonene (also known as D-Limonene), as its name implies, delivers a scent similar to citrus fruits, including grapefruit, lemon, lime, and orange. In terms of medicinal efficacy, this major (primary) terpene acts as an antioxidant, anti-inflammatory (good for sufferers of arthritis, cancer, and fibromyalgia), and anti-cancer (like other terpenes and cannabinoids, it has been shown to shrink cancerous tumors). Similar to other terpenes, limonene is commonly used in beauty products, cleaners, food flavoring, medicine, and perfumes.
Beyond its distinctive and alluring aroma, limonene delivers a wide range of medical efficacies, making it a molecule of interest to many within the patient and medical communities. These benefits include its role as an antiasthmatic (driven by its anti-inflammatory properties), which helps those suffering from asthma, bronchitis, and sinus allergies.
Limonene is found most commonly in the cannabis strains Durban Poison, Jack Herer, and Super Lemon Haze, among others. Interesting facts: Limonene is toxic to aquatic life and, as a standalone molecule, is flammable and considered a biofuel.
The Research
A variety of research studies support the medicinal efficacy of the cannabis terpene limonene, indicating the usefulness of this molecule for patients suffering from conditions ranging from gallstones to asthma to Crohn’s disease.
A 1991 human clinical trial study of 200 patients conducted in Japan entitled “Medical Dissolution of Gallstones: Clinical Experience of D-limonene as a Simple, Safe, and Effective Solvent” and published in the journal Digestive Diseases and Sciences involved the injection of a limonene-based preparation into the biliary systems of patients in an effort to prevent the surgical removal of gallstones.
In nearly half of the study participants (48 percent of the cases), the gallstones “completely disappeared.” Partial dissolution occurred in 15 percent of study participants given limonene to eradicate their gallstones.
A 2017 study entitled “D-limonene Exhibits Anti-inflammatory and Antioxidant Properties in an Ulcerative Colitis Rat Model” that was published in the journal Molecular Medicine Reports concluded that “D-limonene has been demonstrated to have important immunomodulatory properties, including antitumor effects, and may alleviate asthma and allergies.”
Due to its anti-inflammatory effects, limonene was revealed through this research to reduce damage to the intestinal mucosa, thus assisting in the prevention and treatment of gastrointestinal conditions such as ulcerative colitis disease.
A study published in 2014 entitled “Skin Repair Properties of d-Limonene” that was published in the journal Anti-Inflammatory and Anti-Allergy Agents in Medicinal Chemistry found that limonene possesses “tissue-repair properties.”
Concluded the study’s researchers, “D-limonene reduced the severity and extension of skin lesions with significantly lowered macroscopic and microscopic scores.” This research revealed that limonene sometimes demonstrates significant anti-inflammatory effects with respect to the healing of wounds.