Limonene

ˈli-mə-ˌnēn | Noun

A terpene recognizable for its zesty citrus fragrance, primarily in lemon, but also in orange, lime, and grapefruit. Limonene is found in the peels of these citrus fruits and in many varieties of cannabis. Along with myrcene, limonene is one of the most abundant terpenes to occur in cannabis. The terpene has also been explored for its many and varied medical uses, including its anti-inflammatory, anti-anxiety, antibacterial and anticancer qualities.

 

I don’t just smell lemon in my weed with limonene; I’m feeling all the citrus fruits.

 

The holistic doctor prescribed medicine with limonene to ease the patient’s heartburn.

More About Limonene

In addition to its prominent presence in many varieties of cannabis, limonene occurs naturally in mint, juniper, rosemary, pine, and fennel. Some of these sources, such as rosemary, are channeled in essential oil form for therapeutic purposes including scalp massage and in muscle balms. For industrial purposes, limonene has diverse uses: as an organic herbicide, a solvent to remove oil from machinery, and a paint stripper. In traditional medicine, the terpene has been tapped for centuries as a component of remedies for bronchitis, heartburn and gallstones. Modern medicine is now delving into the therapeutic possibilities of limonene and many other terpenes, such as caryophyllene.  

Limonene in Everyday Life

You have probably gotten a whiff of limonene if you have scrubbed your home with any lemon or citrus-scented spray cleaner. In fact, indigenous populations have taken advantage of limonene’s antimicrobial properties for centuries. The terpene is a popular ingredient in household cleaning agents as well as cosmetics, fragrances and body creams. However, in high concentrations, limonene is considered to be a skin irritant that could trigger contact dermatitis for those with an allergy to the terpene. On the dining table, you have experienced limonene when sinking your teeth into a citrus fruit or when indulging in a sweet treat such as chocolate-covered orange peels. Fruity beverages such as lemonade and citrus-flavored ice cream are two other culinary interactions you may have had with limonene.

Therapeutic Properties of Limonene

Limonene is one of the most well-studied terpenes found in cannabis, and has a variety of effects on the immune system. Its antibacterial and antimicrobial effects are well established, and it is currently being studied for its potential to combat mood disorders, diabetes, and cancer among other ailments.

Anti-anxiety

Essential oils that contain limonene are widely used by humans to treat conditions such as anxiety and insomnia. To validate these uses, a 2013 study published in BMC Complementary and Alternative Medicine examined the ability of limonene to reduce depression and anxiety in rodent models of these disorders. Although the researchers found no evidence for the antidepressive effects of limonene, it improved anxiety-like states by interacting with the brain’s serotonin system.

Antioxidant and Anti-inflammatory

Using an animal model of ulcerative colitis, a 2017 study published in the journal Molecular Medicine Reports demonstrated limonene’s ability to reduce disease activity and organ damage. These effects were due in part to the terpene’s antioxidant and anti-inflammatory properties, which have been reported by other researchers as well.

Analgesic

The antiinflammatory and antioxidant properties of limonene may partially explain why it consistently reduces pain across several animal models. The terpene even appears to be an effective topical pain reliever, as demonstrated in a 2016 study in the European Journal of Pain.

Diabetes

A 2016 report in the journal Life Sciences examined limonene’s potential as a novel treatment for diabetes. Using cultured cell models, the researchers demonstrated that the terpene was able to enhance the energy expenditure of white fat cells, essentially making them more closely resemble the body’s “good” fat cells (brown adipose). This effect on metabolism could mean a big shift toward burning, rather than storing excess energy inside the body. In fact, Turkish researchers have subsequently shown that limonene can improve symptoms and act as an antioxidant in animal models of diabetes.

Anticancer

Limonene has demonstrated prospective anticancer properties in many studies, including one published in New Zealand journal OncoTargets and Therapy. Researchers experimented on the lung cancer cells of mice and found that limonene inhibited the growth of the cells while suppressing the proliferation of transplanted tumors. Another study, published in 2009 in the Indian Journal of Carcinogenesis, determined that limonene could be used as a possible treatment for certain types of prostate cancer. In addition, a 2012 study published in the journal Life Sciences, demonstrated that as part of a blood orange oil emulsion, limonene could kill human colon cancer cells. The study went on to assert that this particular emulsion could even offer hope for the prevention of cancer. While these findings are optimistic, clinical trials examining limonene’s efficacy in treating humans suffering from cancer are still needed.

Role of Limonene in Cannabis

There are numerous cannabis varieties with high levels of limonene, not limited to Dirty Girl, Lemon G, Emerald Jack, Cookies and Cream, Shining Silver Haze and Liberty Haze. While you may detect a lemon scent and flavor in some limonene-rich cannabis varieties, you may also perceive a non-specific citrus quality. Some cannabis varieties with limonene possess other potent citrus aromas and tastes, such as tangerine, so your experience will not be the same across the board. Although limonene’s ability to reduce anxiety in animals is an interesting finding, more research is needed to understand how this terpene could benefit humans.

Bottom Line

Among the most common terpenes found in cannabis, limonene is notable for its aromatic, flavorful citrus profile and potential as an anti-inflammatory and anticancer agent.