Interest in the healing ability of essential oils continues to grow with remarkable results in practice being obtained. Nature in her infinite wisdom has given us a potent array of natural medicines and anti-cancer compounds found abundantly in citrus fruits high in D-Limonene, i.e. lemon, orange, grapefruit, tangerine and lime.

Citrus oils generally are high in limonene, specifically D-Limonene, and citral. Citral has been shown to help with fat burning and obesity. We’ll explore citral another time.

Today, let’s talk about D-Limonene. More than 200 research studies have now been conducted on D-Limonene alone. D-Limonene has been primarily researched for:

1. Anticancer effects
2. Dissolves cholesterol
3. Relieves heartburn
4. Aids in weight loss
5. Mild appetite suppressant
6. Prevents weight gain

The peel of these fruits from which essential oils are derived contain the highest percentage of D-Limonene.

General Guide Limonene Content in Citrus Essential Oils
The GC/MS Report will show you the exact percentage of limonene in your essential oil.

• Orange essential oil: 85-99.5% limonene
• Tangerine essential oil: 85-98.6% limonene
• Grapefruit essential oil: 85-96% limonene
• Mandarin essential oils: 65-75% limonene
• Lemon essential oil: 59-79.4% limonene
• Lime essential oil: 50-60% limonene

Though extremely concentrated (a little goes a long way) citrus oils are relatively inexpensive compared to other essential oils. The oil is extracted through cold pressing the fresh peel. It takes about 25 lemons to make one 5ml bottle of lemon oil.

A naturally occurring monoterpene, D-Limonene is produced by a variety of plants. Its strong odor acts as protection for the plants that produce them by deterring predators, as well as attracting pollinators (like bees).

Monoterpenes are the primary constituent of many essential oils, as well as many types of plants and flowers. Because of strong odor molecules essential oils are used widely in the fragrance and perfume industry, as well as in medicine, often masking the offensive odor of pharmaceutical drugs, and alternative forms of medicine like aromatherapy.

Examples of monoterpene and monoterpene alcohols: 

• Geraniol (present in geranium oils and palmarosa)
• Limonene (present in citrus fruits like lemon)
• Llinalool (present in many flowers like lavender and spice oils like clove)
• Pinene (present in pine)
• Terpineol (present in lilacs)
• Myrcene (present in hops)

For decades scientists have studied the phytochemical (plant-based chemicals) found in citrus essential oils. The citrus phytochemical limonene found in citrus oils has been found to have anti-cancer activity, dissolve cholesterol and has been used clinically to dissolve cholesterol-containing gallstones. It is also thought to be effective for treating a fatty liver. D-Limonene may also be used to relieve heartburn, because it can neutralize stomach acid, as well as supports healthy peristalsis.

Cancer Research

A 2015 study conducted on human pancreatic cancer cells in vitro (in test tubes) found that limonene inhibited cancer cell growth. It also inhibited rapid proliferation of cellular growth, as well as apoptosis (programmed death of cancer cells). Studies also noted that limonene had “cancer specific toxicity,” meaning it specifically targets cancer cells.

A small 2013 study of 43 women in the early stages of breast cancer (all of whom were scheduled for surgery) took two grams of limonene per day for two to six weeks prior to their surgery. The studies indicated that limonene specifically concentrated in breast tissue and reduced cyclin D1 expression in tumors. Cyclin D1, a protein involved in the cell’s life cycle was reduced. The study indicated the reduction of cellular expression can lead to cancer cell arrest and reduction in tumor cell growth.

Another clinical study of patients with advanced cancer was conducted with D-limonene. Phase 1 of the study showed the, “tumor suppressive chemopreventive activity of monoterpenes.”

How to Use

1. Dispense 1 drop of your citrus oil on a cotton ball or smell strip and simply inhale for several cycles of breathing. The oils will immediately enter your blood stream by way your lungs and be distributed throughout your entire body. The limonene content stimulates blood cell production and boosts your body’s immune system to fight infection and helps detoxify your organs and systems. Citrus oils are also known for their antidepressant effects and are helpful for relieving stress.
2. Add a drop of your favorite citrus oil to a teaspoon of honey, or favorite carrier and swirl into your beverage for a refreshing respite in your day. Refreshes and brings clarity to your mind.
3. Use in your diffuser and diffuse into the air to lift your mood and aid mental clarity. Blend with lower note spice oils like cinnamon for longer lasting effect.
4. Substitute citrus essential oil in your recipes that call for lemon or other citrus. Remember a little goes a long way 1 drop of lemon oil is equal to the zest of about 4 lemons.