In the world of cannabis, terpenes are asserting their rightful place as one of the key ingredients for the maximum effect of a specific strain on a specific medical condition.
These aromatic chemical compounds provide health benefits by themselves, but also aid the compounds that are unique to cannabis – the versatile cannabinoids, which include tetrahydrocannabinol and cannabidiol — to perform more effectively in what’s colloquially known as the entourage effect, where the active ingredients of the cannabis plant provide the biggest health impact when used in combination.
Terpenes are produced in trichomes (the glands that create resin rich in cannabinoids) of cannabis flowers, where they protect the most important part of the plant against predators.
Each cannabis strain has its own distinctive terpene profile, consisting of numerous different terpenes.
With advancements in botanical sciences, modern growers can increase both the cannabinoid and terpene levels to precisely target the desired effects of that particular strain.
If you’ve missed our piece that thoroughly covers terpene science, or if you’re generally unfamiliar with this subject matter, I suggest you give it a read before continuing, as it’ll help you properly understand the effects of limonene, plus it has an awesome easy-to-digest interactive graphic covering all of the most important terpenes in pot.
A single strain of pot has only a portion of those 200, and most of them are found in trace amounts.
We should now go through the composition of limonene, before we start discussing its benefits and valuable medical uses.
What is limonene?
Limonene is a monoterpene, found as a clear and colorless oil in the peel of citrus fruits like lemons, oranges, grapefruits, limes and pomelos.
Limonene belongs to a group of compounds called terpenes — volatile aromatic molecules produced by plants to either deter herbivores with a potent scent or to attract the predators and parasites of these herbivores.
Terpenes are also frequent constituents of complex chemical compounds, like steroids.
Because of its versatility, limonene is used in dietary supplements, cosmetics, bathing products, and perfumes. It is also frequently used as an ingredient in cleaning products, and because of its combustible nature, it’s considered as a possible bio-fuel in the future.
Biggest health benefits of limonene
Because it can be extracted from plants other than cannabis, the research on the effects of limonene is quite extensive.
Limonene has shown promise as an:
- Antiproliferative agent, spreading the advancement of cancer cells
- Anti-inflammatory agent, helping with conditions like Alzheimer’s, Crohn’s, Irritable Bowel Syndrome and Fibromyalgia
- Antibacterial agent
- Antifungal agent
It is also beneficial for:
- Depression, anxiety and stress, acting as a mood elevator
- Acid Reflux (heartburn), and also aids in dissolving gallstones
Limonene also enhances the way our body absorbs cannabinoids and other terpenes, either through the mucous membranes, digestive tract, or the skin.
Let us now explore what the recent clinical research has to say on this amazing terpene.
Studies on the health effects of limonene
Note: When reading this research, keep in mind that these studies were conducted using therapeutic doses of pure limonene. For example, the patients in the first study were taking two grams of limonene daily. Cannabis only has a trace or very small amounts of limonene and using cannabis does not guarantee any of the health benefits found in these studies.
2013 and 2015 — The University of Arizona Cancer Center
Both of these preclinical studies were conducted at the Cancer Center of the University of Arizona and found that limonene indeed helps with the reduction of cancer-cell proliferation (1). Introducing limonene to the cancer cultures also reduced the size of the analyzed tumors.
The first study analyzed samples from 43 women who had this early stage breast cancer.
The other preclinical study found that from 397 identified metabolites, 72 significantly reduced in size after limonene administration. The authors of the study concluded:
“Future controlled clinical trials with limonene are necessary to determine the potential role and mechanisms of limonene in the breast cancer prevention setting.” (2)
2011 — The University of Arizona Cancer Center
This preclinical study was also performed at the Cancer Center in Arizona, on cell cultures and animals. Limonene from citrus peels displayed promise for treating cancer, showing upon ingestion a wide range of chemopreventive and chemotherapeutic effects. (3)
Perillyl alcohol (which is the analog of limonene) was also tested, and while it also showed promise and even more powerful effects, because of the high toxicity of perillyl alcohol the clinical trials were stopped, and the scientists continued to focus on limonene.
Unlike perillyl alcohol, limonene was very well tolerated, and even as its mechanisms aren’t yet figured out by the researchers, the anti-cancer and immune modulating effects are more than verifiable.
2012 — Hamdard University, India
Mainly observing the inducement of apoptosis (cell-suicide) from the introduction of the terpene limonene, this particular study also examined its chemopreventive and antiproliferative effects on skin tumor cultures of mice.
The results showed that there was a significant reduction in tumor size, and limonene was also slowing down the overall progress of the examined skin cancers. (4)
The team in charge of this research concluded that the combination of several beneficial effects of limonene including the diminishment of inflammation, lessening of oxidative stress and apoptotic inducement make this terpene a great ally in the battle against skin carcinoma.
2011 — Unidade de Pesquisa Clínica, Brazil
Conducted on perillyl alcohol, or POH (which is a metabolite of limonene), this research examined the effects of POH on patients who have recurrent malignant glioma, more precisely glioblastoma (also called GBM).
The team was looking into the potential and efficiency of intranasal administration of POH, in regards to halting and arrestment of gliomagenesis (the advancement of GBM).
The research was conducted on 89 adults with recurrent glioblastoma who received 440mg of POH on a daily basis, and 52 adults who only received supportive treatment, without perillyl alcohol.
The results of this study showed that the group who was administering POH survived significantly longer, and the side effects of perillyl alcohol were practically nonexistent, even with patients who were using it for a period of over 4 years. (5)
2014 — Biopark Campus Cancer
Focusing on the anti-inflammatory and tissue healing properties of limonene, this study analyzed its effects on macroscopic and microscopic lesions. Limonene and its metabolite perillyl alcohol showed significant influence on the reduction of severeness of skin lesions, expediting the healing processes.
The scientists concluded that limonene acts as a powerful apparatus for epidermal healing, and can also be used as an effective anti-inflammatory medicine. (6)
2010 — Dept. of Environmental Medicine, Kochi Medical School, Japan
This study from Japan also focused on the anti-inflammatory effects of limonene, obtained from the peel of Yuzu fruit (citrus junos), which is used as a traditional medicine for centuries, and studied it on human eosinophilic leukemia cells.
There is a lot more research which proves the helpfulness of this molecule for a wide variety of diseases and ailments. We’ll now divert our attention on the strains which are most abundant with this amazing terpene.
5 strains rich in limonene
Because of its high THC levels, this potent Indica is perfect for chronic pain and insomnia, but it also produces some powerful munchie effects. The rich aroma of Kosher Kush is predominantly citrusy but also has a luxurious earthy note to it.
As a direct descendant of the famed OG Kush strain, it has won two Cannabis Cup’s for Best Indica in 2010 and 2011.
CBD Medihaze (Boaty McBoatface)
This specially bred medical strain has a refreshing lemon-like limonene aroma to it, and because of its high CBD levels, it’s perfect for epilepsy patients, as well as those seeking relief from anxiety, Parkinson’s, and inflammation.
Besides the citrusy taste, CBD Medihaze also offers a rich minty and honey flavors to the mix.
Bonanza (Borealis Blend Sativa)
This blend is a mixture of several Sativa strains which are pre-milled for easier consumption by the consumer, and the fragrance of this particular blend is a combination of sweet, citrusy and skunky aromas, all rolled into one.
Bonanza is a fantastic choice for casual daytime consumption, causing mostly euphoric and energetic sensations.
Odin 2 (Sour Diesel 2)
This 90% sativa strain has around 15% THC, which makes it an intermediately potent cannabis variety. The buds are extremely dense, with orange and pink notes covering the dark green base of the flower. The taste is mostly sour, with a pleasant but not overwhelming hint of diesel, while the fragrance of the bud (once it’s sparked) can be described as a pine, diesel and musky/earthy combination.
As most sativas, it works wonders for depression and anxiousness, hitting that euphoric sweet spot along the way.
A crossbreed of Sensi Star and Afghani, Argyle is an Indica dominant, with an almost 1:1 ratio of THC and CBD. This ratio makes it perfect for various occasions, as the CBD cannabinoids lower the psychoactive effects of THC wonderfully. Regarding the taste and aroma, pine is the key fragrance, with a woody and honey tones which underline it.
Expect severe munchies with Argyle, and slight couch-locking is a possibility, which is dependant on your personal chemistry.
- Miller JA, Lang JE, Ley M, Nagle R, Hsu CH, Thompson PA, Cordova C, Waer A, Chow HH; Human breast tissue disposition and bioactivity of limonene in women with early-stage breast cancer; June 2013; 577-84
- Miller JA, Pappan K, Thompson PA, Want EJ, Siskos AP, Keun HC, Wulff J, Hu C, Lang JE, Chow HH; Plasma metabolomic profiles of breast cancer patients after short-term limonene intervention; January 2015; 86-93
- Jessica A. Miller, Patricia A. Thompson, Iman A. Hakim, H.-H. Sherry Chow, Cynthia A. Thomson; d-Limonene: a bioactive food component from citrus and evidence for a potential role in breast cancer prevention and treatment; October 2011; 31-42
- Chaudhary SC, Siddiqui MS, Athar M, Alam MS; D-Limonene modulates inflammation, oxidative stress and Ras-ERK pathway to inhibit murine skin tumorigenesis; August 2012; 798-811
- da Fonseca CO, Simão M, Lins IR, Caetano RO, Futuro D, Quirico-Santos T; Efficacy of monoterpene perillyl alcohol upon survival rate of patients with recurrent glioblastoma; February 2011; 287-93
- d’Alessio PA, Mirshahi M, Bisson JF, Bene MC; Skin repair properties of d-Limonene and perillyl alcohol in murine models; March 2014; 29-35
- Hirota R, Roger NN, Nakamura H, Song HS, Sawamura M, Suganuma N; Anti-inflammatory effects of limonene from yuzu (Citrus junos Tanaka) essential oil on eosinophils; April 2010; 87-92