What Is Limonene? Everything You Need to Know

Limonene is the oil extracted from the peels of oranges and other citrus fruits (1).

People have been extracting essential oils like limonene from citrus fruits for centuries. Today, limonene is often used as a natural treatment for a variety of health issues and is a popular ingredient in household items.

However, not all of limonene’s benefits and uses are supported by science.

This article examines limonene’s uses, potential benefits, side effects, and dosage.

Limonene is a chemical found in the rind of citrus fruits, such as lemons, limes, and oranges. It is especially concentrated in orange peels, comprising around 97% of this rind’s essential oils ( 2 ).

It’s often referred to as d-limonene, which is its main chemical form.

Limonene belongs to a group of compounds known as terpenes, whose strong aromas protect plants by deterring predators ( 3 ).

Limonene is one of the most common terpenes found in nature and may offer several health benefits. It has been shown to possess anti-inflammatory, antioxidant, anti-stress, and possibly disease-preventing properties.

Summary

Limonene is an essential oil found in citrus fruit peels. It belongs to a class of compounds called terpenes.

Limonene is a popular additive in foods, cosmetics, cleaning products, and natural insect repellants. For example, it’s used in foods like sodas, desserts, and candies to provide a lemony flavor.

Limonene is extracted through hydrodistillation, a process in which fruit peels are soaked in water and heated until the volatile molecules are released via steam, condensed, and separated (4).

Due to its strong aroma, limonene is utilized as a botanical insecticide. It’s an active ingredient in multiple pesticide products, such as eco-friendly insect repellents (5).

Other household products containing this compound include soaps, shampoos, lotions, perfumes, laundry detergents, and air fresheners.

Additionally, limonene is available in concentrated supplements in capsule and liquid form. These are often marketed for their supposed health benefits.

This citrus compound is also used as an aromatic oil for its calming and therapeutic properties.

Summary

Limonene is used in a range of products, including food, cosmetics, and eco-friendly pesticides. It can also be found in supplement form, as it may boost health and fight certain diseases.

Limonene has been studied for its potential anti-inflammatory, antioxidant, anticancer, and heart-disease-fighting properties.

However, most research has been conducted in test tubes or on animals, making it difficult to fully understand the role of limonene in human health and disease prevention.

Anti-inflammatory and antioxidant benefits

Limonene has been shown to reduce inflammation in some studies ( 6 , 7 ).

While short-term inflammation is your body’s natural response to stress and is beneficial, chronic inflammation can harm your body and is a major cause of illness. It’s important to prevent or reduce this type of inflammation as much as possible ( 8 ).

Limonene has been shown to reduce inflammatory markers that relate to osteoarthritis, a condition characterized by chronic inflammation.

A test-tube study in human cartilage cells noted that limonene reduced nitric oxide production. Nitric oxide is a signaling molecule that plays a key role in inflammatory pathways ( 9 ).

In a study in rats with ulcerative colitis — another disease characterized by inflammation — treatment with limonene significantly decreased inflammation and colon damage, as well as common inflammatory markers ( 10 ).

Limonene has demonstrated antioxidant effects as well. Antioxidants help reduce cell damage caused by unstable molecules called free radicals.

Free radical accumulation can lead to oxidative stress, which may trigger inflammation and disease ( 11 ).

One test-tube study revealed that limonene may inhibit free radicals in leukemia cells, suggesting a decrease in inflammation and cellular damage that would normally contribute to disease ( 12 ).

Although promising, these effects need to be confirmed by human studies.

May have anticancer effects

Limonene may have anticancer effects.

In a population study, those who consumed citrus fruit peel, the major source of dietary limonene, had a reduced risk of developing skin cancer compared to those who only consumed citrus fruits or their juices ( 13 ).

Another study in 43 women recently diagnosed with breast cancer experienced a significant 22% reduction in breast tumor cell expression after taking 2 grams of limonene daily for 2–6 weeks ( 14 ).

Additionally, research in rodents found that supplementing with limonene inhibited the growth of skin tumors by preventing inflammation and oxidative stress ( 15 ).

Other rodent studies indicate that limonene may fight other types of cancer, including breast cancer ( 16 ).

What’s more, when given to rats alongside the anticancer drug doxorubicin, limonene helped prevent several common side effects of the medication, including oxidative damage, inflammation, and kidney damage ( 17 ).

Although these results are promising, more human studies are needed.

May boost heart health

Heart disease remains the leading cause of death in the United States, accounting for nearly one in four deaths ( 18 ).

Limonene may lower your risk of heart disease by reducing certain risk factors, such as elevated cholesterol, blood sugar, and triglyceride levels.

In one study, mice given 0.27 grams of limonene per pound of body weight (0.6 grams/kg) showed reduced triglycerides, LDL (bad) cholesterol, fasting blood sugar, and fat accumulation in the liver, compared to a control group ( 19 ).

In another study, stroke-prone rats given 0.04 grams of limonene per pound of body weight (20 mg/kg) exhibited significant reductions in blood pressure compared to rats of similar health status that did not receive the supplement ( 20 ).

Keep in mind that human studies are needed before strong conclusions can be drawn.

Other benefits

Aside from the benefits listed above, limonene may:

• Reduce appetite. The scent of limonene has been shown to significantly reduce appetite in blowflies. However, this effect has not been studied in humans ( 21 ).
• Decrease stress and anxiety. Rodent studies suggest that limonene could be used in aromatherapy as an anti-stress and anti-anxiety agent ( 22 ).
• Support healthy digestion. Limonene may protect against stomach ulcers. In a study in rats, citrus aurantium oil, which is 97% limonene, protected nearly all of the rodents against ulcers caused by medication use ( 23 ).

Summary

Limonene may offer antioxidant, anti-inflammatory, anticancer, and anti-heart-disease benefits, among others. However, more research in humans is needed.

Limonene is considered safe for humans with little risk of side effects. The Food and Drug Administration (FDA) recognizes limonene as a safe food additive and flavoring (5).

However, when applied directly to the skin, limonene may cause irritation in some people, so caution should be used when handling its essential oil ( 24 , 25).

Limonene is sometimes taken as a concentrated supplement. Because of the way your body breaks it down, it’s likely safe consumed in this form. That said, human research on these supplements is lacking ( 26 ).

Notably, high-dose supplements may cause side effects in some people. What’s more, insufficient evidence exists to determine whether limonene supplements are acceptable for pregnant or breastfeeding women.

It’s best to consult your healthcare practitioner before taking limonene supplements, especially if you’re taking medications, are pregnant or breastfeeding, or have a medical condition.

Summary

Aside from possible skin irritation associated with direct application, limonene is likely safe for most people to use and consume in moderation.

Because few limonene studies exist in humans, it’s difficult to provide a dosage recommendation.

Nonetheless, dosages of up to 2 grams daily have been safely used in studies ( 9 , 14 ).

Capsule supplements that can be purchased online contain dosages of 250–1,000 mg. Limonene is also available in liquid form with typical dosages of 0.05 ml per serving.

However, supplements aren’t always necessary. You can easily obtain this compound by eating citrus fruits and peels.

For example, fresh orange, lime, or lemon zest can be used to add limonene to baked goods, drinks, and other items. What’s more, pulpy citrus juices, such as lemon or orange juice, boast limonene, too ( 27 ).

Summary

While dosage recommendations don’t exist for limonene, 2 grams daily has been safely used in studies. In addition to supplements, you can obtain limonene from citrus fruits and zest.

Limonene is a compound extracted from the peels of citrus fruits.

Studies suggest that limonene may have anti-inflammatory, antioxidant, and anticancer effects. However, more research in humans is needed to confirm these benefits.

Try adding lemon, lime, or orange zest to your favorite dishes to boost your limonene intake.