What Is Limonene and What Does This Cannabis Terpene Do?
Josh Kaplan and Bailey Rahn contributed to this story. Updated 3/27/2019.
Limonene is an aromatic cannabis terpene
produced in the flower’s resin glands. In isolation, it’s commonly associated with fruity, citrus aromas, and it’s found in many everyday items like fruit rinds, cosmetics, and cleaning products.
While limonene is often assumed to be abundant in strains that smell like lemon
, this isn’t always the case. When seeking strains high in limonene, you’ll need to find lab-tested products to know that the strain you’re buying is in fact limonene-packed.
Whereas THC typically makes up 10-30% of a flower’s dry weight, limonene occurs in trace amounts, generally between 1-2%.
High Limonene Cannabis Strains
Some strains exhibit higher levels of limonene than others, but these levels can vary widely across harvests depending on genetics, growing techniques, and curing processes. The only way to know if your strain is high in limonene is through lab-tested batches.
According to lab data from Confidence Analytics
in Washington, strains that tend to produce high levels of limonene on average include:
Limonene’s Effects and Benefits
Despite limonene’s potential therapeutic benefits, little is known about how it works in the brain and body, and what doses are required to achieve these benefits. In many of the limonene studies to date, high doses were used—much higher than amounts found in cannabis. More cannabis-focused research is needed, but studies on limonene so far have shown potential in the following applications:
- Elevated mood
- Stress relief
- Antifungal properties
- Antibacterial properties
- May help relieve heartburn and gastric reflux
- Improves absorption of other terpenes and chemicals by way of the skin, mucous membranes, and digestive tract
There’s also promising evidence for limonene’s anti-tumor effects. In lab rodents, limonene inhibited the growth of skin
tumors. These studies were followed up with a Phase I human clinical trial which found that limonene was somewhat effective at reducing breast cancer tumor growth
for nearly a year. Later studies found that daily limonene supplementation
for 2-6 weeks silenced a protein that promotes breast cancer tumor growth, suggesting that daily limonene consumption may inhibit the growth and spread of breast tumors.
Additional reports have revealed benefits of limonene in laboratory models of lung cancer
and brain cancer
by causing tumor cell death. But like limonene’s benefits in breast cancer, high doses are likely needed beyond what may be present in cannabis alone. It’s unknown, however, whether the presence of certain cannabinoids extends limonene’s anti-cancer effects. Currently, there is not nearly enough evidence to conclude that cannabis products high in limonene will be effective as cancer treatments in humans.
Future Research on Limonene
It remains unclear how limonene achieves its therapeutic effects. Inhalation of limonene vapor increases serotonin
and dopamine levels in key regions of the brain that are associated with anxiety, depression, and OCD. Does limonene merely stimulate the brain’s olfactory system, or is it directly affecting brain cells themselves? We don’t yet know.
By better understanding limonene’s targets in the brain and body, scientists may help direct users towards strains or products where limonene’s therapeutic benefits are optimized by a particular cannabinoid and terpene profile.
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