Terpenes are aromatic oils found in the trichomes of the cannabis plant that give different strains their distinctive tastes and smells. Along with cannabinoids, terpenes are responsible for various physiological effects on the human body.1 With more than 10,000 terpenes identified and 10 to 30 predominant types present in any given cannabis plant, there are endless strain varieties.
Different strains, or chemotypes, of cannabis have distinctive compositions and concentrations of terpenes, causing differences in medicinal and intoxicating effects between strains. Although some differences between varieties may be subtle, terpenes can broaden the therapeutic value of cannabis through their unique medicinal properties and psychoactive effects—and science on their potential health benefits continues to emerge.
Clinical evidence points to both cannabinoids and terpenes as disease mediators. Many theories suggest that it’s the “entourage effect” that has the greatest likelihood of producing the most significant reduction in systemic pain and other symptoms. The entourage effect refers to the potential cannabis synergy and complementary pharmacological activities between phytocannabinoids and terpenoids.2 If evidence continues to support phytocannabinoid-terpenoid synergy, there’s a greater likelihood that new research and new therapeutic products will be developed to treat common conditions.
Preclinical evidence bolsters the idea that terpenoids can provide adjunctive support to the mechanisms of the cannabinoids; that evidence “supports the concept that selective breeding of cannabis chemotypes rich in ameliorative phytocannabinoid and terpenoid content offers complementary pharmacological activities that may strengthen and broaden clinical applications and improve the therapeutic index of cannabis extracts.”2
One lesser-known terpene is delta-3-carene, also called carene. In addition to cannabis, it’s found in plants such as pine, cedar, rosemary, and basil. While the number of studies is limited, carene is being researched for its role in human health as a potential anti-inflammatory and antifungal and for its ability to support bone health. Carene is found in higher concentrations in several cannabis strains, including Jack Herer, Super Lemon Haze, and AK-47. It has a sweet, earthy aroma with lemon and pine undertones. Anecdotally, cannabis consumers report that carene elicits a sense of euphoria, calm, and enhanced mood while promoting memory retention and alertness.
A 2019 study published in the Journal of Ethnopharmacology examined the anti-inflammatory and antinociceptive effects of the active ingredients in the essential oils from Gynura procumbens (GPEO). GPEO, sometimes called “longevity spinach,” is an
edible vine used in traditional Chinese medicine.
Traditionally applied topically for the treatment of traumatic injury, it’s also becoming a popular food. Research demonstrates that GPEO contains carene as a main active ingredient.3 In a study that examined the anti-inflammatory and antinociceptive effects in vivo and in vitro of mice, it was found that mice treated with GPEO or its active ingredients—alpha-pinene, 3-carene, and limonene—experienced a decrease in pain and swelling compared with controls.3 This suggests that carene may possess some anti-inflammatory and antinociceptive effects. This effect, whether seen in GPEO or cannabis, needs further study in humans.
A 2006 study published in the Journal of Applied Microbiology aimed to determine whether essential oils extracted from trees and shrubs of the genus Juniperus exhibited antifungal activity. This research determined that essential oils extracted from Juniperus oxycedrus subsp. oxycedrus are mainly composed of alpha-pinene (65.5%) and delta-3-carene (5.7%). Results suggested that juniper essential oil may be an emergent alternative as an antifungal agent against dermatophyte strains, and delta-3-carene was shown to be fundamental for this activity.4
Dermatophytosis, commonly known as ringworm, is a highly contagious fungal infection of the skin or scalp. These preliminary findings suggest that the topical application of carene, whether from juniper essential oil or cannabis oil, may be beneficial as a therapeutic alternative to resistant antifungal drugs. Researchers concluded that these findings justify the need for future clinical trials to support the use of carene and essential oils as therapeutic alternatives for common fungal infections.4
In 2007, a rodent study published in Phytotherapy Research suggested that a low concentration of carene had an effect on the bone health of mice. The carene in this study was extracted from pine trees, not cannabis plants, and significantly stimulated the activity and expression of alkaline phosphatase while catalyzing calcium induction in a dose-dependent manner. The researchers concluded that essential oils and other additives to the diet could benefit bone health.5 While the results of study may not apply to human bone health, further scientific research in humans may be warranted.
While most terpenes are Generally Recognized as Safe by the FDA, there have been anecdotal reports that high concentrations of carene are associated with dry eyes and mouth. It’s important for practitioners to be aware that this can be a very unpleasant sensation for many cannabis consumers.
While more research is needed on the potential for delta-3-carene in cannabis to help promote human health, preliminary evidence suggests that further research is warranted. In the meantime, clinicians can become familiar with this terpene and what strains of cannabis contain it, and use this knowledge to better guide patients toward the best strain for their particular health circumstance. Clinicians should also be aware that this terpene may cause some discomfort for patients when used in large amounts and be able to guide their patients away from strains high in this terpene if persistent dry eyes and mouth become a problem. n
— Emily Kyle, MS, RDN, CDN, CLT, HCP, is a certified holistic cannabis practitioner.
1. Backes M. Cannabis Pharmacy: The Practical Guide to Medical Marijuana. New York, NY: Black Dog & Leventhal; 2017.
2. Russo EB. Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects. Br J Pharmacol. 2011;163(7):1344-1364.
3. Huang XL, Li XJ, Qin QF, Li YS, Zhang WK, Tang HB. Anti-inflammatory and antinociceptive effects of active ingredients in the essential oils from Gynura procumbens, a traditional medicine and a new and popular food material. J Ethnopharmacol. 2019;239:111916.
4. Cavaleiro C, Pinto E, Gonçalves MJ, Salgueiro L. Antifungal activity of Juniperus essential oils against dermatophyte, Aspergillus and Candida strains. J Appl Microbiol. 2006;100(6):1333-1338.
5. Jeong JG, Kim YS, Min YK, Kim SH. Low concentration of 3‐carene stimulates the differentiation of mouse osteoblastic MC3T3‐E1 subclone 4 cells. Phytother Res. 2008;22(1):18-22.