Continuing our series on the major terpenes found in cannabis, we move on to limonene, which, as its name suggests, is also found in citrus fruits such as lemons and oranges. Because of its distinctive fruity smell, limonene is commonly used in household cleaning products and cosmetics, while it can also be detected in the aroma and flavour of popular cannabis cultivars such as Super Lemon Haze, Banana Kush and Wedding Cake.
How Much Limonene Is Present In Cannabis?
As we’ve explained in our previous posts, terpenes are aromatic compounds that contribute to the unique smell and taste of each strain of weed, while also interacting with cannabinoids and other compounds in order to influence a cultivar’s pharmacological and medical properties.
However, while you might expect all cultivars that have ‘Lemon’ in their name to be loaded with limonene, the reality is that this terpene is usually quite scarce, occurring only in trace amounts in most cannabis varieties. For that reason, it’s difficult to know exactly how much sway this terpene has over the effects of a given cultivar, and while some research has been conducted into the medical benefits of limonene, most studies have used large concentrations of the terpene that typically exceed those found in cannabis.
In spite of this, limonene is recognised as one of the most important terpenes present in cannabis, and while some uncertainty remains regarding its effects, there’s no doubt that it contributes significantly to the overall experience delivered by certain cultivars.
The Benefits Of Limonene
While no major studies have been conducted using cannabis-derived limonene, a fair amount of research has been carried out into the medical benefits of citrus-derived limonene. For instance, researchers have found that aromatherapy using bitter orange essential oil reduces anxiety in mice, and that this effect is mediated by limonene’s ability to bind to serotonin receptors in the brain[i].
A similar essential oil was found to significantly decrease pain in women during labour[ii], while lemon essential oil helped to alleviate nausea and vomiting during pregnancy[iii]. Interestingly, recent research has shown that smoking weed helps with morning sickness, though no research has yet been conducted into the efficacy of limonene-rich cultivars for this purpose.
Perhaps the most significant benefit of limonene, however, is its apparent ability to facilitate cancer treatments. In one study, the terpene prevented the spread of lung cancer in mice by upregulating genes that are associated with tumour cell death[iv]. A further study revealed that limonene may be effective against skin cancer, in part due to its ability to attenuate inflammation and oxidative stress[v].
Yet another study – this time conducted on human participants – found that limonene helps to treat breast cancer by reducing the expression of a protein called cyclin D1, which is generally amplified in this particular type of cancer[vi].
On top of all this, limonene has been shown to aid tissue healing in mice. It is thought that this occurs thanks to one of the terpene’s metabolites called perillyl alhocol, which inhibits the release of inflammatory proteins known as cytokines[vii]. Finally, the compound has also been used to successfully treat neuropathic pain in mice, while simultaneously reducing signs of depression[viii].
As previously mentioned, none of these studies apply specifically to limonene that has been ingested via cannabis, although with so many medical benefits having been identified, calls are growing for more research to be conducted into this cannabis terpene.
[i] Costa CA, Cury TC, Cassettari BO, Takahira RK, Flório JC, Costa M. Citrus aurantium L. essential oil exhibits anxiolytic-like activity mediated by 5-HT 1A-receptors and reduces cholesterol after repeated oral treatment. BMC complementary and alternative medicine. 2013 Dec;13(1):1-0. – https://link.springer.com/article/10.1186/1472-6882-13-42
[ii] Namazi M, Akbari SA, Mojab F, Talebi A, Majd HA, Jannesari S. Effects of citrus aurantium (bitter orange) on the severity of first-stage labor pain. Iranian journal of pharmaceutical research: IJPR. 2014;13(3):1011. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4177623/
[iii] The Effect of Lemon Inhalation Aromatherapy on Nausea and Vomiting of Pregnancy: A Double-Blinded, Randomized, Controlled Clinical Trial – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4005434/
[iv] Yu X, Lin H, Wang Y, Lv W, Zhang S, Qian Y, Deng X, Feng N, Yu H, Qian B. D-limonene exhibits antitumor activity by inducing autophagy and apoptosis in lung cancer. OncoTargets and therapy. 2018;11:1833. – https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5894671/
[v] Chaudhary SC, Siddiqui MS, Athar M, Alam MS. D-Limonene modulates inflammation, oxidative stress and Ras-ERK pathway to inhibit murine skin tumorigenesis. Human & experimental toxicology. 2012 Aug;31(8):798-811. – https://journals.sagepub.com/doi/abs/10.1177/0960327111434948
[vi] Miller JA, Lang JE, Ley M, Nagle R, Hsu CH, Thompson PA, Cordova C, Waer A, Chow HS. Human breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer. Cancer Prevention Research. 2013 Jun 1;6(6):577-84. – https://cancerpreventionresearch.aacrjournals.org/content/6/6/577.short
[vii] A d’Alessio P, Mirshahi M, Bisson JF, C Bene M. Skin repair properties of d-Limonene and perillyl alcohol in murine models. Anti-Inflammatory & Anti-Allergy Agents in Medicinal Chemistry (Formerly Current Medicinal Chemistry-Anti-Inflammatory and Anti-Allergy Agents). 2014 Mar 1;13(1):29-35. – https://www.ingentaconnect.com/content/ben/aiaamc/2014/00000013/00000001/art00005
[viii] Piccinelli AC, Santos JA, Konkiewitz EC, Oesterreich SA, Formagio AS, Croda J, Ziff EB, Kassuya CA. Antihyperalgesic and antidepressive actions of (R)-(+)-limonene, α-phellandrene, and essential oil from Schinus terebinthifolius fruits in a neuropathic pain model. Nutritional neuroscience. 2015 Jul 1;18(5):217-24. – https://www.tandfonline.com/doi/abs/10.1179/1476830514Y.0000000119