Limonene is a type of terpene, commonly found in cannabis on the trichome glands located on the flowers of the plant.
Limonene is commonly used in cleaning products as a solvent and candles for its aroma. When you’re walking through your supermarkets cleaning aisle, and it smells like lemons this is probably why!
Outside of their industrial use, terpenes are known for giving cannabis (both hemp and street weed) its sometimes pungent aroma along with unique flavour.
However, these organic compounds are much more than pure flavour enhancers. They are also thought to influence the way cannabinoids interact with our endocannabinoid system along with having their own unique effects when used in isolation.
Let’s dive further to discuss what is Limonene and how this essential oil has been the focus of multiple research studies:
What is it and is it natural?
Limonene is a natural and organic compound from a family of plant metabolites called terpenes.
It can be found in two different chemical forms, which are both located in various plants, and the limonene structure is as follows:
- D-Limonene found abundantly in the peels of lemons or oranges and cannabis. Also extractable in lower concentrations from rosemary. It smells like citrus fruits and is often used in soaps, fragrances, detergents, insecticide and chewing gum.
- L-Limonene is less common and found primarily in pine needles or cones. Has a turpentine-like scent and is often used in industrial cleaning products.
Where is Limonene found?
While Limonene is widely available through nature, it is possible to recreate synthetic terpenes such as man-made copies of the compound.
However, these are a minority in the marketplace and are used as solvents for cleaning if at all. Most people/businesses use naturally extracted Limonene from plants (like us!), especially if adding it to food or drink.
It’s even possible you have also consumed D-limonene without knowing it in the last month or at the very least used it in cleaning products!
Well, that’s because outside of cannabis D-limonene is found in high concentrations and in isolation in the peels of citrus fruits. In particular, orange rind, which contains over 97% limonene essential oils.
Looking more closer to home, if you have tried freshly squeezed oranges or lemon juice, you will know the juice can make your cheeks squelch in line with the taste of the bitter lemon or orange – this effect can be partially attributed to the Limonene in citrus fruits.
If you can think of any food or drink with citrus in, it probably has D-limonene in. Fail that, if you have any lemon cleaning products in your cupboard they are likely rich in the terpene.
The fact that most people like the fragrance of citrus, you can also often find Limonene at your local car wash stacked up in-car air fresheners, and in the chemical sprays they use for cleaning.
So now you know it smells nice and where to find it, you’re probably looking for the answer to the following question:
What are the benefits of Limonene?
Researchers believe that terpenoids like Limonene can work synergistically with the cannabinoids found in cannabis to improve the effects felt by users.
This is the basis of what is colloquially known as the entourage effect, where the effect of the sum of each compound is far greater than each one used in isolation.
Outside of this phenomenon, terpenes have been the basis of a variety of research studies. Analysing their unique effects when used both in isolation and in combination with multiple cannabinoids like THC and CBD.
D-Limonene might be anti-inflammatory and an antioxidant
D-Limonene has been shown to reduce inflammation in multiple studies, including a pre-clinical study on colitis with rats in 2013 and again a similar analysis (in rats) in 2017 both concluding that it has anti-inflammatory properties.
The compound has also demonstrated antioxidant properties in the same 2017 study linked above. Antioxidants can assist in fighting free radicals in your body. An excess of free radicals is linked to diseases, including breast cancer.
A 2009 population study explored the relationship between the consumption of citrus peel (the most common source of d-limonene) and cancer. Finding that participants who had consumed the citrus rind had a reduced risk of developing skin cancer than those who had not.
Heart health studies
Pre-clinical research suggests that Limonene can potentially impact cholesterol levels, and as a consequence, indirectly improve heart health (assuming everything else is equal).
In one study, mice were given limonene equivalent to 0.6 grams per kg of weight, leading to reduced cholesterol and a significant lowering of blood pressure.
In another study, rats were fed a high-fat diet for 12 weeks along with a 2% limonene solution for the final 4 weeks of the study. Rats showed an increased level of blood pressure and concentration of body fat in the first 8 weeks, which then reduced significantly in the last 4 weeks.
Early Liver Disease Detection and Limonene
Liver cirrhosis is often a product of alcoholism, and it is usually diagnosed too late in the cycle to regulate the disease, leading to increased healthcare costs and demand for transplants.
A recent study by the University of Birmingham concluded that Limonene holds potential as an early marker for liver disease via patient breath samples. They found that pre-transplant patients had extremely high levels of Limonene in their breath, much higher than levels found in a healthy person.
The researchers hypothesised that this was due to the body being unable to process Limonene while suffering from liver disease. Later finding that post-transplant, the same patients had a much lower level of Limonene in their breath.
Concluding that excess Limonene levels could prove fruitful as a potential early sign marker for liver disease, which otherwise would be unlikely to be diagnosed.
Limonene Allergy & Contact Dermatitis
While Limonene isn’t toxic to humans, as with almost anything, it’s possible to be allergic to it. This can lead to contact dermatitis (an itchy, red allergic skin rash) when a product containing Limonene is applied directly to the skin.
It’s also possible to suffer limonene allergy only via external exposure to Limonene while being completely fine if drinking orange or lemon juice.
Although this isn’t too common, it’s something to be aware of if adding d-limonene to your skin or using cleaning products with it in. It may also irritate the respiratory tract, as well.
Limonene and CBD Products
Limonene is one of the most common cannabis terpenes, in that it’s found in a large variety of strains including different types of hemp. As a result, it’s commonly found in some form in full or broad-spectrum CBD Oil.
Although, it’s not something you would be able to recognize immediately without looking at a third party terpene test to review what terpenes the product contains and in what quantity.