Terpenes, volatile compounds regarded as essential oils from a plant, have been a buzzword for the cannabis industry for some time now. These aromatic molecules give plants, particularly the cannabis plant, its bouquet of fragrance. The terpene craze has replaced the fervor that the term cannabinoids used to have within the industry and the mainstream. As more people have begun to understand that there is more to this plant than its cannabinoids (especially the CBD and THC molecules), it has helped consumers look for products that are more suited for their needs. In fact, a product with an aroma that is pungent and suited to one’s tastes is going to have a more desirable effect than if it were a single isolate product without any fragrance.
Spicy, earthy, fruity, and skunky are all words used to describe some of the cannabis aromas. For some, this plant reeks and assaults their nose, but for others these aromas intrigue and invite the individual to partake in its consumption. Everyone has a personal preference for fragrances, whether that is for perfumes, food, spices, or cosmetics; cannabis products are no different. In this review, we will go over the importance of these phytochemicals in terms of people’s and plants’ health, examine some of the reasons behind the increase of terpene demand for the booming cannabis markets, and explore some common cannabis terpenes.
Terpene Properties for Plant Health and Human Wellness
Humans have long been captivated by the fragrance of plants and how aroma encourages interactions. However, interacting with humans isn’t the sole reason that plant species contain these phytochemicals. Terpenes are often used by plants as a defense against the physical world and attraction for pollinators. As a result, plants have been studied quite extensively regarding their aroma profile in order to reveal more of the mystery behind these oils. Consequently, scientists have been able to identify over 20,000 varieties of terpenes that exist within nature. Many of them are further studied to examine the physiological effects on humans and to understand more of the role they play in plant health. For this discussion, we will focus primarily on monoterpenes, sesquiterpenes, and terpenes as a whole instead of covering all of them individually.
Monoterpenes are extremely fragrant compounds. A majority of essential oils contain monoterpenes since they are the major class of chemicals within a plant’s essential oil. It is postulated that monoterpenes serve the purpose of attracting pollinators and also as a repellant from grazing organisms. Sesquiterpenes are larger, heavier compounds compared to monoterpenes. They are believed to have evolved as a response to fungal attacks, herbivore grazing, and they also attract pollinators. This culmination of protective qualities safeguards the plant from pathogens, predators, and environmental stressors. Additionally, they promote pollinator attraction to ensure reproduction is fulfilled.
Aromatic plants have been traditionally used as a form of spiritual therapy for cleansing spaces. Today essential oils are commonly used for cleansing the air from airborne viruses and bacteria, not to mention for promoting certain moods. Some common effects people receive from inhaling aromatics are support for mood and cognition as well as immune system support. Some studies have indicated these terpenes are responsible for certain mood-enhancing effects such as calming, energizing, focusing, and uplifting. For example, lavender has been studied extensively for its calming effects which shows the properties of linalool– the primary terpene constituent. Certain terpenes have properties that provide defense against bacteria, microbes, and viruses; this is evident by the number of cleaning products, body care products, and pesticides that utilize terpenes in their formulation (Joshee et al., 2019).
An interesting debate occurring within the cannabis industry is the argument over the existence of the entourage effect. First introduced by Mechoulam and Ben-Shabat, Israeli scientists in the late 1990s, this is the theory that cannabinoids and other chemical compounds like terpenes found in cannabis resin elicit a strong synergistic effect. The entourage effect refers to a synergy between various phytochemicals within cannabis: that major and minor cannabinoids along with terpenes contribute to the overall pharmacological effect. Anecdotal accounts from users describe the effect as feeling balanced and the positive feelings enhanced. Supporters of the entourage effect point to the number of side effects people encounter after using a single molecule substance. The neurologist, cannabis researcher, and entourage effect advocate Ethan Russo cites an example of a clinical trial of Sativex (a pharmaceutical-grade drug derived from cannabis which is composed of a mixture of THC and CBD) in which people reported more pain relief than their counterparts who received exclusively THC or a placebo. There are other studies that suggest certain terpenes have the potential to reduce memory problems induced by THC, illustrating the effect terpenes exhibit when working with cannabinoids in concert.
Unfortunately, there are not enough proper studies and clinical trials to truly validate this theory; skeptics point to the extreme variability of the chemical compounds and the inability to measure terpene concentration within the body after consumption. Skeptics are also worried that this debate will uphold anecdotal and personal experiences over scientific methods. Until we can dive further into this research, which includes double-blind clinical trials, we cannot prove the existence of the entourage effect and elucidate how it works (Worth, 2019). Some scientists even argue that this theory may be unprovable due to the scientific challenges posed to properly test cannabis. People are left to their own conclusions if a full spectrum product (containing CBD as well as other cannabinoids and terpenes) works better than a single isolate product.
Industry Demand
Terpenes play a critical role in the cannabis puzzle. They make finished goods more palatable and potentially offer additional wellness benefits, as well as assist in altering formulation viscosities. Most of the products available on the market are infused goods like topicals, sublingual tinctures, and food and beverages. In order to stand out amongst the competition, companies have realized they need to hone in on flavor and smell to make creative and appealing products. This is why terpenes are in serious demand.
People want flavorful products and they will often pay more for this quality. Consumers are fortunate to have a huge selection to choose from because of this demand. Many of the terpene-rich products that are cannabis-derived are made for smoking or vaporizing, such as concentrated oil for vape cartridges, “dabbing” (which is just a way of vaporizing oil using a heated apparatus), and the traditional smoking of the plant material. For masking the smell and taste of extracted cannabis in an infused product, terpenes are sourced from other plants to be utilized because not everyone likes the cannabis aroma and it saves money on not using cannabis-derived terpenes. This is due to the small yield of terpenes extracted from the specific plant material, so a lot of processors utilize terpenes from different plant sources where there is more of an abundance and is more cost-effective. What is also interesting to note is that some extracted oils do not contain terpenes because they are lost in the extraction process, so formulators must have some kind of reintroduction of terpenes.
The 2019 “vaping crisis” alerted the cannabis community that there were certain practices that needed to be avoided. Manufacturers were employing innovative and unfortunately cheap methods to save money and to get ahead in the market. As a result, people were vaping oil that contained vitamin E acetate, as well as other unsavory thinning agents and additives. Whereas terpenes are an excellent thinning agent, and albeit costlier option, it makes the most sense health-wise and ultimately encourages brand trust. These natural oils change the viscosity of vaping oil which is safer than vitamin E acetate or coconut oil. It’s even better if it’s sourced from the same extracted plant.
Consumers benefit from being able to choose fragrant products because our olfactory senses connect us to our memories, to spoiled food, to poison, and more. This natural attribute could really help people seek out flower options and product variety that would suit them and their needs. Our nose knows what we like!
Common Cannabis Terpenes
The main two types of terpenes found within cannabis varietals include monoterpenes and sesquiterpenes, but these appear as either major or minor compounds. They only account for a small percentage of the total constituents often between 2-5%, but their odorous presence is very distinct and unmistakable (Erickson, 2019). The trichomes are the structures that create these secondary metabolites in order to protect the plant from UV rays, fungal attacks, and predators. Depending on how each plant grew will ultimately determine the amount and content of terpenes.
Each plant has its own variation of terpenes in different concentrations. If one were to compare an outdoor-grown plant to an indoor-grown one, the difference in smell is palpable, for the sun-grown plant exhibits a stronger and more complex terpene profile due to the environmental stressors it encountered. Another interesting comparison of terpene differentiation is to take two plants of the same variety that were grown in different locations to examine the aroma profile. They will be drastically different. There will always be a lot of variation in the volatile oils due to the growing conditions and genetics.
Consumers will find that cannabis varieties, also known as cultivated varieties (cultivars), contain many different types of terpenes, but there are a number of familiar ones found in common plant species. The charts below briefly examine terpenes that are present in major and minor amounts within the chemical profile. Recall that there are over a hundred various terpenes found within a single cannabis plant (Booth & Bohlmann, 2019). Therefore, this review is not intended to provide a comprehensive summary. It takes a look at a terpene’s role for the plant, other sources of the volatile oil, the odor impression and notes that there are studied properties that can be extrapolated for future and further investigation for the pharmaceutical, nutraceutical, and aromatherapy industries.
Common Cannabis Monoterpenes and Sesquiterpenes
The Ultimate Plant Communication
In the words of the herbalist Tammi Sweet, “terpenes are a whole medicinal apothecary unto themselves” (Sweet, 2020). We have a natural ability to seek out and discern scents that intrigue, delight, or repel us. Our sense of smell is an extremely powerful tool, one that should be entrusted with more authority over our preferences for aromas and tastes. Understanding how this element works within the cannabis industry is a huge advantage over those who don’t understand how to confidently choose infused products. Trust your senses, look to the plants for guidance, and educate yourself about the incredible world of fragrance, for it is awe-inspiring how plants are able to interact and communicate with their entire world merely through their phytochemistry.
References
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