What is Limonene?

The Buzz Around D-Limonene

Knowledge is power, and the more we can educate ourselves about the world of medicine, the more empowered we become to make empowered decisions surrounding our health.

Today, we'll be unpacking Limonene (sometimes referred to as D-Limonene).

Limonene is one of the most commonly occurring terpenes, found in a wide variety of MC strains and the citrusy fruits its name denotes (as well as juniper, peppermint, rosemary and grapefruit). As the name suggests, limonene brings with it aromas of sweet, citrusy goodness that make it an ideal natural additive for food, beverages and cosmetics.

Medicinal Use

Like its other terpene brothers and sisters, limonene is utilised for a wide range of medicinal benefits. Improvements in digestion, memory and mood enhancement, limonene has proven efficacy in managing the symptoms of anxiety and depression.

Furthermore, limonene contains significant anti-inflammatory properties. These anti-inflammatory properties are especially valuable for the hundreds of diseases and conditions related to inflammation, including asthma, arthritis and chronic pain.

Limonene has also been found to combat acid reflux (including heartburn) and dissolve gallstones. Finally, limonene in large doses can act as an appetite suppressant, indicating its potential to be used as an effective ingredient in future weight loss drugs and therapies.

The Studies

In 2014, a study published in the Anti-inflammatory and Anti-allergy Agents in Medicinal Chemistry journal titled "Skin Repair Properties of d-Limonene in Murine Models" demonstrated that limonene contains potent anti-inflammatory qualities that are of specific value to cancer patients.

In an excerpt from this study, the researchers claim that "d-Limonene and POH (Perillyl Alcohol) demonstrate significant anti-inflammatory effects in murine dermal inflammation and wound-healing".

The 2014 study deduced that limonene has the "surprising" capability to inhibit tumours from spreading to surrounding tissue by preventing cancer cells from growing new blood vessels (effectively starving them to death). This research also revealed that limonene may regenerate skin and tissue by enhancing re-epithelialisation (actively bringing new cells to damaged areas).

In 2011, a clinical trial study entitled "Limonene Study in Women with Breast Cancer" involving 59 human participants demonstrated that limonene may be a promising prophylactic and therapeutic treatment for breast cancer. The researchers concluded that "Limonene has demonstrated promising breast cancer preventative and therapeutic effects in preclinical model systems". Whilst this is a step in the right direction and the results are promising, the world of cancer is extremely complex, nuanced and subject to a vast range of biological, social and environmental factors. More research is required to gain better understanding of limonene's interactions with cancer.

In a recent study published in the medical journal Neurophysiology, limonene was found to provide significant improvement in spacial memory and symptoms of anxiety, indicating strong neuro-protective properties. Limonene not only increases serotonin availability, but is an agonist of the adenosine receptors that trigger the release of dopamine. This study also indicated limonene's potential efficacy in treating neurodegenerative diseases such as dementia, alzheimers and MS.

Finally, a 2010 study conducted at the Kochi Medical School titled "Anti-inflammatory Effects of Limonene on Eosinophils" and published in the Journal of Food Science revealed limonene to be an effective treatment for altered bronchial functioning stemming from inflammation (such as asthma). It was shown that limonene may be effective in treating symptoms of asthma via inhibiting cytokines, ROS production and inactivating eosinophil migration.