Essential oils, the concentrated plant extracts boasting volatile organic compounds (VOCs), are well-known for their distinctive aroma and flavour. Terpenes, a large, diverse category of VOCs, are the primary contributors to the scent and taste of these oils. Found in various natural sources like fruits, vegetables, herbs, spices, and flowers, terpenes lend their qualities to more than just sensory experiences.
Terpenes influence essential oils’ therapeutic effects on the body and mind. Interacting with numerous biological systems—including the nervous, immune, endocrine, and digestive—terpenes can modulate their functions and responses. They also can sway mood, cognition, memory, and behaviour, thereby impacting the experience of essential oil users.
Certain essential oils with a high terpene content offer more distinct aromatherapy, health, and wellness benefits.
For instance, citrus essential oils, including lemon, orange, grapefruit, and bergamot, abound in monoterpenes such as limonene. These monoterpenes have uplifting, energizing, and antibacterial properties.
Pine oil is rich in pinene, which has anti-inflammatory, broncho-dilating, and memory-enhancing effects. Likewise, rosemary oil, with its camphor content, offers stimulating, analgesic, and antiseptic properties. Linalool and linalyl acetate in lavender oil bring calming, relaxing, and antispasmodic properties.
This article aims to educate readers on the chemical composition, properties, and benefits of terpenes in essential oils. By understanding the chemistry behind essential oils and terpenes, readers can better appreciate their significance in aromatherapy, health, and wellness. Furthermore, it guides the reader on the safe and effective use of terpene-rich essential oils based on their specific needs.
Types of Terpenes in Essential Oils
Terpenes are natural compounds synthesized from isoprene units, five-carbon molecules with a branched structure. Their biosynthesis follows two primary pathways: the mevalonate and the methylerythritol phosphate pathway, producing isopentenyl pyrophosphate (IPP) and dimethylallyl pyrophosphate (DMAPP). These units then combine to form various types of terpenes, such as monoterpenes, sesquiterpenes, and diterpenes, among others.
Monoterpenes are composed of two isoprene units or ten carbon atoms. They are abundant in essential oils and usually emit a strong, pleasant aroma. Examples include limonene, pinene, myrcene, linalool, and menthol. Their molecular structures vary from acyclic, monocyclic, to bicyclic, depending on how the isoprene units are connected.
Sesquiterpenes are built from three isoprene units or 15 carbon atoms. Less volatile than monoterpenes, they are important due to their significant biological and pharmacological properties. Examples include farnesene, caryophyllene, humulene, and bisabolol.
Sesquiterpenes often have more complex structures than monoterpenes, such as tricyclic or tetracyclic, and frequently contain oxygen-based functional groups.
Diterpenes, made of four isoprene units or 20 carbon atoms, are typically found in resinous plants or parts, such as conifers or ginkgo. Examples are abietic acid, kaurene, phytol, and taxol. Diterpenes exhibit diverse molecular structures, often with multiple functional groups.
Bioactivity and Applications of Terpenes in Essential Oils
Terpenes in essential oils offer a broad spectrum of bioactivity, contributing to human health and well-being. They modulate physiological and psychological processes, including inflammation, pain, infection, mood, memory, and stress. Furthermore, they interact with different molecular targets in the body, such as receptors, enzymes, ion channels, and transporters. Through these interactions, terpenes alter membrane fluidity and permeability, impact signal transduction pathways and gene expression, scavenge free radicals, and enhance antioxidant defense systems, among other effects.
There’s an increasing body of scientific evidence that supports the benefits of terpenes in essential oils for various conditions and diseases. For example, limonene exhibits anti-inflammatory, anticancer, antidiabetic, antidepressant, and anxiolytic effects in animal and human studies. Similarly, pinene possesses anti-inflammatory, antimicrobial, analgesic, bronchodilator, neuroprotective, and memory-enhancing properties. Linalool, too has demonstrated anti-inflammatory, antimicrobial, antifungal, insecticidal, and analgesic effects.
Guidelines for Using Essential Oils Rich in Terpenes
Before applying essential oils to the skin, always dilute them with a carrier oil like coconut, almond, jojoba, or olive oil. The typical dilution ratio is 1-2% for adults and 0.5-1% for children, equating to 6-12 drops of essential oil per ounce of carrier oil for adults and 3-6 drops per ounce for children.
Store essential oils in a cool, dark, and dry place, away from heat, light, and moisture, to prevent the oxidation and degradation of terpenes and other constituents.
Exercise caution when using essential oils during pregnancy, breastfeeding, or if you have any medical conditions or allergies. Some essential oils may interact with certain medications or supplements. Always consult your doctor or a certified aromatherapist before using essential oils therapeutically.
You can diffuse essential oils in a room using a diffuser, a humidifier, or a spray bottle. This not only creates a pleasant and relaxing atmosphere but also purifies the air and eliminates odours.
Dosage for a diffuser: Typically, 3-5 drops of essential oil per 100 ml of water.
Applying essential oils topically as a massage oil, lotion, cream, or salve can deliver terpenes and other compounds to target areas, providing localized relief or benefits. Avoid applying essential oils to sensitive areas, such as the eyes, ears, nose, mouth, genitals, or wounds.
Inhalation directly from the bottle, a cotton ball, a tissue, or an inhaler can stimulate the olfactory system and the brain, providing systemic effects via the bloodstream.
Dosage for inhalation: Typically, 1-2 drops of essential oil per session. However, do not inhale essential oils for more than 15 minutes at a time, and take breaks between sessions.
The role of terpenes in essential oils is paramount, influencing not only the aromatic and flavour profiles but also the therapeutic and physiological effects these oils have on the human body and mind. Each category, from monoterpenes to sesquiterpenes and diterpenes, contributes distinct properties and benefits. With the growing scientific evidence, we’re increasingly understanding the positive impact these terpenes can have on many conditions and diseases.
In the contemporary landscape, the best natural ones are even being added to vape cartridges, enhancing the sensory experience while potentially offering therapeutic benefits. However, it’s essential to remember that using essential oils requires careful handling and informed decision-making. Always ensure to dilute the oils, store them correctly, and consult with a professional if you have any medical conditions or are pregnant or breastfeeding.
The topical application, diffusion, or inhalation of these oils can offer various benefits, but the key is to do so wisely and safely. As we delve deeper into the chemistry of essential oils and terpenes, we continue to unlock these natural compounds’ rich potential for our health and well-being. The captivating world of terpenes in essential oils holds promising vistas for aromatherapy, health, and wellness, inviting us to explore and appreciate the remarkable chemistry of nature.