Limonene Cannabis Terpene: Effects, Sources, and Cannabis Strains
Introduction
Terpenes, as discussed in previous articles, are extremely important organic compounds found all over the planet in plants and animals. Cannabis, especially with modern cross breeding is the richest and most abundant source of a spectrum of terpenes known to humanity.
Terpenes have many uses in nature; to be alluring to animals for pollination purposes, to protect against the sun, for communication between plants, and in the case of the skunk, protection from predators.
Modern cannabis science, despite being held back by misguided laws, has managed to progress to a point where we now know many more useful things about how terpenes and indeed cannabinoids interact with the body and the ecosystem as a whole.
Limonene, or more accurately D-Limonene, is extremely common in both cannabis and the rest of nature. It is in the top 3 most common terpenes found in cannabis, along with beta-caryophyllene and myrcene. Found in citrus fruits, it smells fresh, fruity, sweet and a little tart. In cannabis, flavonoids also help bring the citrus aroma. Limonene, which has been studied for properties such as antioxidant and anti-inflammatory activity, is often described as an uplifting and energizing terpene, and it is most associated with the morning.
Aromatherapy is a big part of how people talk about wellness, and terpenes are central to it. People come across terpenes in many forms, from cannabis to fresh fruit to extracts, and each one carries its own aroma and character.
Limonene in Nature
Limonene is the second most commonly found terpene in nature after pinene, found in pine, other conifer trees and many more plants.
Limonene occurs naturally in many places in nature. It occurs in citrus fruits like lemons, limes, oranges, grapefruits and is more concentrated in the skin of these fleshy fruits. Limonene can be extracted from the skin of these fruits to produce aromatic oils. Citrus skin, dried and used as air freshener, is also a very common and old practice.
Limonene is also found in non citrus fruits. It’s found in rosemary, peppermint and juniper among others. Rosemary contains several terpenes also shared with cannabis and is used frequently in cuisine and traditional medicine. Rosemary tea is often reported to be highly energizing, an effect which may be supported by limonene. Juniper is an integral ingredient of gin, which owes much of its taste to limonene and pinene.
When limonene is in the flowers of the plant it can repel or attract insects for pollination, which is a common use for terpenes. Limonene, when exuded underground, from the roots of the plant, slows and prevents growth of other species of plants in the surrounding area.
Limonene in Detail
Limonene is a monocyclic-terpene and not a terpenoid, meaning there is no oxygen in the molecules. The ‘monocyclic’ refers to a ring formation in its structure giving it a higher boiling point than terpenes without one.
Limonene actually has two versions of itself that are like molecular mirror images sort of like your left and right hand. D-limonene or ‘R’ version is the one found in citrus fruits and cannabis. L-limonene or ‘S’ version is not found in cannabis but is found in pine and mint plants giving a distinctive minty aroma. We can see the connection between these two versions in fresh smelling candy or cleaning products based around citrus or mint.
Other limonene derivatives are also very common in nature and cannabis. Carvone, the active ingredient in spearmint seed oil and alpha-terpineol which is found in cardamom and pine, are in the limonene family. Another derivative is 1,8-cineole which is actually the eucalyptus terpene.
Limonene in Research
Limonene is often referred to as the happy terpene, and anecdotal reports associate it with an uplifting, energizing feeling. It can also trigger olfactory memories, like many terpenes, which can induce nostalgia. Its bioavailability is high, around 70%, which is part of why it is so linked with aromatherapy, since much of it is taken in simply by breathing the aroma.
When combined with THC it is said to have a cerebral and euphoric entourage effect. Limonene has been associated with anxiolytic (anti-anxiety) and antidepressant effects in some studies. The anti-anxiety effects are thought to be mediated by the serotonin receptors as limonene may influence serotonin levels in the prefrontal cortex and could potentially impact dopamine levels in the hippocampus.
Limonene has also been studied in connection with the immune system and, like many terpenes, for anti-inflammatory properties. Some research has looked at how it may interact with the body’s balance of energy and resources.
Limonene is present in many different sources. Each source brings its own entourage of compounds, except isolated limonene, which is essentially orange peel extract. Interestingly, orange oil contains around 90% limonene while lemon oil contains about 68% limonene with 16% b-pinene and 12% g-terpinene.
Pure limonene extract, essentially an orange peel supplement, has been discussed in relation to digestion and acid reflux, and it is sometimes described as having antimicrobial properties. Dosing matters, since too much can disrupt the balance of bacteria. One commonly noted side effect is orange tasting burps.
Limonene has been explored for its potential anti-cancer properties in research. Studies suggest that limonene may disrupt signals sent to cancer cells within a tumor. This might inhibit the cells from multiplying and could potentially lead to their death, a process known as “apoptosis”.
Limonene and the Circadian Rhythm
Limonene being an energizing terpene means that it can affect your circadian rhythm, which is our cycle of wakefulness and sleepiness. The day or wakeful state is called catabolic; it produces energy and helps break down tissue for regeneration. Anabolic states refer to sleepiness or nighttime state where the body is very good at repairing and rebuilding our body and mind.
When individuals experience too much catabolic or day state, they may report symptoms such as insomnia, loose stools, a rise in insulin resistance, and a perceived lack of recovery time. Too much anabolic state and you can experience constipation, anxiety, tachycardia (fast resting heart rate), or in some cases hard tumours.
Limonene is pro catabolic, so people who are already highly catabolic may notice more of those day state effects. For that reason limonene is usually associated with the morning, while other terpenes like myrcene or caryophyllene are pro anabolic and more associated with night time.
Naturally occurring limonene has been part of diets around the world for a very long time. The benefits of lemons are famously healthy for a wide range of reasons across many cultures. In relation to acid reflux, isolated limonene is something some people have looked into.
Fruits, spices and cannabis each contain their own entourage of compounds, and each interacts with the body differently. Learning where these compounds come from adds to a broader understanding of plants and diet.
High Limonene Cultivars
The limonene content of a cultivar will have a very significant impact on the level of energizing compared to calming. High limonene contents are common in sativa hybrids and sativa landraces. However it can also appear in some indica strains in small amounts.
Kush Mints is a popular, equally balanced hybrid often described as both relaxing and energizing, which some people associate with creative tasks. It has a distinctive minty fresh flavor with gassy undertones. Users frequently describe it as euphoric, and it is generally talked about as a daytime rather than a nighttime cultivar.
Durban Poison is a landrace sativa native to South Africa. It’s popular for its fruity fresh aroma and its uplifting, energizing character. It is also often associated with creativity and daytime use.
Banana Kush is a hybrid strain known for its energizing character. It has a distinctive banana smell, and some users describe a mellow, sociable quality and find it keeps them talkative in social settings.
Ref: Study, leafly, blog, blog
Conclusion
Limonene is one of the most widespread terpenes there is. It shows up in fruits and herbs all across the planet and has been part of many people’s diets for thousands of years, woven into ordinary life for much of that time.
We now know that it is the same compound behind the energizing aroma of lemon, rosemary, cannabis and much more, which connects a lot of everyday plants and foods.
Many strains carry limonene, and those highest in it are most associated with the daytime rather than the evening, in line with the terpene’s energizing reputation.