Terpenes are Aroma Therapy

Excerpted from Weed: A Connoisseur’s Guide to Cannabis

Fog rolls over the hillsides on an early morning hike. As sunbeams break through the mist, they activate the aromas of the chaparral: the nuanced and layered sweetness of a bay laurel, with its touches of eucalyptus, pine and bergamot; the small bright yellow florets of fennel that form a bouquet bearing a burst of licorice and sweet anise.

The aromatic elements of the natural world, the same ones that are steam-distilled to create essential oils found in food and fragrances, play a vital role in mental and physical well-being. The essences pulled from plants are called both terpenes and terpenoids. The terms are used interchangeably, but they are different in chemical structure. Terpenes are simple hydrocarbons, an organic chemical compound composed exclusively of hydrogen and carbon atoms. Terpenoids are also essentially terpenes, but with additional chemical constituents, most often oxygen, as a result of enzyme-driven reactions within the plant.

“Think of it like terpenoids equal terpenes plus chemically modified terpenes,” cannabis researcher Ryan Lee explains. “Like if someone did a renovation to a house and added a different back porch.”

Terpenoids and terpenes are the aromatic elements that give cannabis its deep depth of incredible fragrances and tastes. As the science behind how cannabis works continues to advance, studies show that not only do they make cannabis smell amazing, but they also play an essential role in understanding exactly how this plant shapes our moods.

“Terpenoids modify the cannabis experience in a variety of ways, and can make it more or less sedating, extend therapeutic benefits, and potentially make cannabis safer and better overall,” explains Ethan Russo, one of the world’s most prominent and well-respected cannabis researchers.

Terpenes are found along with cannabinoids in the resin glands of cannabis and many other plants. There are more than 20,000 terpenes identified in nature; about 200 are in cannabis. The genetic diversity of cannabis is vast, each kind contains several different terpenes. That means understanding the scent of cannabis is more akin to a symphony rather than a single note. Layers and nuances of smell ensure that it’s complicated to say a bud smells like only one particular thing.

Tetrahydrocannabinol (THC), the primary cannabinoid that gives cannabis its psychoactive effects, has been the main focus of cannabis research since Raphael Mechoulam synthesized and isolated it in 1964. But cannabinoids such as cannabidiol (CBD) and cannabigerol (CBG) are now gaining increasing attention. Many still may have the misconception that the medicinal effects of cannabis are only about the pharmacology of cannabinoids; they are neglecting about 500 other properties that make up the plant, Russo says. As he explains in his cornerstone cannabis study, Taming THC: potential cannabis synergy and phytocannabinoid-terpenoid entourage effects, the harmony created by how cannabinoids and other properties of the plant such as terpenes work together (something understood in academic cannabis circles as the entourage effect) has significant ramifications in cannabis therapeutics. The idea is that the magic of how cannabis works is in the sum of its parts, rather than by elements in isolation.

“One molecule is unlikely to match the therapeutic and even industrial potential of cannabis itself as a phytochemical factory,” Russo writes in an academic paper making a case for the entourage effect.  

Russo is a board-certified neurologist, pharmacology researcher and former senior advisor to GW Pharmaceuticals. This U.K.-based company made history in 2018 when the FDA approved a drug that contained cannabinoids, Epidiolex. His current company, CReDO Science, is working to patent products generated from his investigations of the cannabis plant. It’s also capitalizing on his understanding of the endocannabinoid system (ECS), the signaling network responsible for regulating many processes in the body that interacts with terpenes as well as cannabinoids produced internally, endocannabinoids, and cannabinoids derived from plants, phytocannabinoids. Understanding the complexities of cannabis can be approached in the same way as traditional Chinese medicine, he says. 

“Traditional Chinese medicine usually combines a variety of ingredients simultaneously. Some may add to the therapeutic effect, while others are included to mitigate adverse events from the primary agents. Both of these activities are synergistic and produce a better clinical response.”

Russo explains that cannabis, with its various cannabinoids and terpenes, is akin to traditional Chinese medicine in that it’s a single preparation that combines a variety of ingredients.

Developing Terpenes

The same chemical components that have protective functioning and beneficial elements in plants can positively contribute to the defense and regulation of systems within our bodies, just like they do for the plant itself. This concept that what benefits the plant that also benefits us also occurs with antioxidants, which plants create to prevent disease; they have a similar function in humans, explaining why a diet high in plants is beneficial for our health. In the same way as antioxidants, terpenes develop in plants to prevent disease for the plant, but they also can help our bodies avoid illness.

As cannabis horticulture expert Ed Rosenthal explains, plants produce terpenes for one of three reasons: to attract pollinators, to repel or kill herbivores, or to attract the predators of herbivores. The odor molecules are costly for the plant to produce and increase when the plant is in flower because it’s invested in its reproduction. Cannabis is wind-pollinated, which means it doesn’t need to attract pollinators. Hence, the benefits of terpenes in cannabis are to keep pests away and attract beneficial insects, which attack the other insects that can damage a crop. 

All About the Aromas

Terpenes unleash concentrated odors that can affect our moods. One of the easiest ways to understand this phenomenon is through citrus, which is a popular aromatic in cleaning products because it acts as both a disinfectant and a deodorizer. Physiologically the smell of citrus denotes cleanliness and has a mood-elevating and immune-stimulating effect. The terpene present in citrus fruits is limonene; it’s also in cannabis cultivars like Do-Si-Dos and MAC (Miracle Alien Cookies). While cultivars named after citrus fruits such as Super Lemon Haze and Lemon G contain some limonene, it’s not the dominant terpene. Super Lemon Haze contains more terpinolene than limonene and Lemon G contains more caryophyllene than limonene. This shows how minor and major terpenes work together to give cannabis its varied effects of scents and tastes. Limes, grapefruits, lemons and oranges are all citrus, but also have other components that give them their distinct individual aromas and flavors.

Russo further explains the concept of terpenes through the Japanese therapeutic practice of shinrin-yoku, or forest bathing. In this form of ecotherapy, participants are invited to take in nature’s sensory elements, savoring the sights, smells, and sounds to unplug and release stress. Pinene is in pine needles, tea tree and rosemary, and cannabis cultivars like Dutch Treat and Jack Herer. It’s the terpene that is most prevalent in nature in both coniferous trees and other plants, and studies have shown it can enhance memory and cognition. Within his academic research paper examining the synergistic components of cannabis, Russo addresses how pinene’s ability to aid memory “could counteract short-term memory deficits induced by THC intoxication.”

Myrcene is the most common terpene in cannabis and has a synergistic effect with THC that enhances its sedative properties. Cultivars that are heavy in myrcene (OG Kush, Granddaddy Purple) are helpful for sleep and are known to produce “couch lock,” which is an effect precisely as it sounds, of being locked to the couch unable to move. Myrcene is also in lemongrass, thyme and mangoes. 

Russo argues that thinking about cannabis beyond THC-heavy strains high in myrcene uncovers more of the plant’s subtle beneficial properties.

“Beyond the common form of cannabis that pervades the markets with its high THC and high myrcene, productive of a soporific ‘couch-lock’ experience, other terpenoids, when present in appropriate concentrations, may alter the experience positively to increase the therapeutic index of cannabis by reducing its side effect profile,” Russo says. “Thus, pinene can reduce or eliminate short-term memory impairment engendered by THC, limonene can elevate mood with an antidepressant effect, linalool will allay anxiety, and caryophyllene boosts analgesic and anti-inflammatory benefits while simultaneously reducing craving that is associated with withdrawal symptoms from opioids and other drugs producing dependency.”

Common Terpenes

Myrcene
Also found in mangoes, hops and lemongrass, myrcene contributes musky, clove-like earthy notes. This terpene works in synergy with THC in amplifying its psychoactive effects. Myrcene is a powerful anti-inflammatory and has shown the ability to improve conditions such as osteoarthritis. 

Limonene
Also within citrus rinds and juniper, limonene contributes sweet fruit scents. Studies show that limonene has antimicrobial and antifungal effects. It is being studied for its ability to inhibit tumor growth and may play a role in treating cancer. 

Caryophyllene
An element of black pepper, caryophyllene has a spicy scent and activates cannabinoid receptors within peripheral tissues, the parts of the body that act as a response to a change in the environment such as skin. It shows promise in treating inflammation, pain, the buildup of cholesterol on artery walls (atherosclerosis), osteoporosis and osteoarthritis.

Pinene
The most common terpene in nature, pinene, is associated with the scent of pine trees and is also found in tea trees and rosemary. It has shown to be useful for retaining and restoring memory. Researchers are looking at pinene in regards to treating conditions such as dementia and Alzheimer’s.

Linalool
Also found in lavender, linalool can produce sedative calming effects and reduce agitation. That means this terpene could have applications in treating conditions such as PTSD. It is also showing promise for its ability to counteract epileptic seizures.

Humulene
In hops, basil, coriander, cloves, ginseng and ginger, humulene has woodsy, earthy flavors and possesses formidable anti-inflammatory properties. It’s best known as the quintessential hoppy flavor in beer.  

Terpinolene
Terpinolene is a terpene in apples and lilacs. Its smells pull from all over the spectrum with a bit of woodsy earth combined with citrusy pine notes. Interest in treatments with this cannabinoid includes coronary heart disease as well as its antifungal properties.

Ocimene
Ocimine is in plants and fruits that have woodsy, sweet undertones. In cannabis ocimene-dominant cultivars are rare. This terpene has flavors of guavas, mangoes, papayas and pine. It’s also in herbs like mint, parsley and basil.