From a twist of lemon in a cup of tea to the “lemon fresh” scent of detergent and furniture polish, just about everyone has encountered the terpene limonene—you just might not have known it. And while limonene can add flavor to foods and a pleasant smell to cleaning products, this common plant oil also has powerful healing properties.
Limonene is one of many terpenes found in marijuana, and it works with cannabis compounds such as tetrahydrocannabinol (THC) and cannabidiol (CBD) to create a synergy that boosts the effectiveness of cannabis for treating pain and the symptoms of many health conditions.
Research on the benefits of cannabis has focused largely on the effects of its cannabinoids, mainly the well-known THC and CBD. Along with these two components, cannabis contains more than a hundred other “ingredients” whose properties haven’t yet been investigated in depth. That includes terpenes, oils produced by the plant’s resin glands—the same ones that also produce THC and other compounds.
Terpenes aren’t unique to cannabis. They’re produced by a number of plants and herbs—and even by some insects. A single plant can contain many different terpenes, but each plant has its own unique terpene profile that’s dominated by one particular terpene. These terpenes can be extracted for a number of purposes, including flavoring and scenting various products, aromatherapy oils, cosmetics and industrial solvents.
The term terpenoids is often used to describe these substances—but terpenes and terpenoids aren’t the same thing. Chemically, terpenes are hydrocarbons, meaning the only elements they contain are hydrogen and carbon. But terpenoids are terpene products that have been altered by other processes such as the oxidation that takes place when flowers and leaves have been cured and dried. Terpenoids may also be synthetically created by combining different terpene molecules or adding elements from other sources.
Because terpenes and cannabinoids such as THC and CBD come from the same source, they work together, each boosting or modifying the effects of the other in a synergy that’s more powerful than each one alone.
Until relatively recently, few studies have explored the role of terpenes in cannabis for medical uses. But those studies reveal that both terpenes and cannabinoids bind to the body’s natural endocannabinoid receptors. And not only do terpenes exert their own influence on those receptors, they can also affect how the receptors respond to THC, CBD and other cannabis compounds.
Limonene is one of the most commonly occurring terpenes in a wide variety of plants. As D-limonene, it’s found in especially high quantities in lemons (hence the name), but also in other citrus fruits, juniper and rosemary. Another variation, L-limonene, is found in pinecones and needles and is used in a variety of industrial solvents and cleaners.
D-limonene, or just limonene, is also found in numerous cannabis strains, mostly sativa. But some indica strains can have significant amounts of this terpene, too. High levels of limonene are responsible for the citrusy, lemony taste and smell of strains like Super Lemon Haze, Sour Diesel and Lemon Skunk. These marijuana strains can be especially effective for boosting energy and reducing stress, along with the many other health benefits of cannabis in general.
Studies have revealed that CBD, the most prevalent non-psychoactive compound in cannabis, acts on the body’s CB1 receptors to affect a long list of processes. That’s why CBD can improve nerve and muscle function in disorders like Parkinson’s disease, reduce inflammation and fight infection, as well as potentially suppress factors that can lead to cancer.
But limonene has those properties all on its own, too. Limonene from any source has been shown to:
Limonene has also been called the “anti-cancer terpene” because preliminary studies have shown that it may even be able to reduce or eliminate certain kinds of cancerous tumors.
In cannabis, limonene can:
Along with the other terpenes in each strain’s unique profile, limonene works with all other parts of the whole plant to support the body’s own healing mechanisms.
One way to get the benefits of limonene is to choose cannabis strains with high amounts of this terpene. But it’s also possible to buy pure terpene extracts, which can be combined with cannabis. Limonene can be added to cannabis-based creams and ointments because it’s easily absorbed through the skin. You can also dip cannabis dabs in limonene extract before placing it on the nail.
Although limonene and other terpenes are generally nontoxic and safe to use, even in pure forms, heating them or burning them at high temperatures can cause their chemical components to break down. That can render them less effective and also cause carcinogens to form—a risk that rises when using dab rigs with no temperature controls.
New research on terpenes in general continues to reveal more about the many ways these essential cannabis components work together and with the body’s own systems to help combat disease and promote wellbeing. This research is also bringing to light that limonene’s own healing properties can boost the effectiveness of key cannabis compounds to bring relief from a long list of health conditions.
Photo credit: liz west