Everything you need to know about essential oils

Essential oils arevolatile essences extracted from aromatic plants. Among all the species that the plant kingdom encompasses, only 4000 contain essences and aromatic molecules. However, only a few hundred contain enough for us to extract essential oils with a significant yield.

From an organoleptic perspective, essential oils can vary in fluidity. They can also be viscous and pasty, but they are always non-greasy. Their scents are quite potent, releasing the aromas of the original plants.

Essential oils arecomplex mixtures combining different compounds(terpenes, alcohols, ketones, aldehydes) that provide numerous benefits, whether throughingestion(internal route),inhalationortopical application(external route).

Even though there are several methods of extracting essential oils from aromatic plants, the low-pressure steam distillation is the most common technique used to extract essential oils from plants. Invented in the 11th century, it involves several steps.

1. The water is brought to a boil within aboilerto capture the steam produced.

2. The plant material to be distilled (flowers, leaves, roots, seeds...) is placed in a copper or stainless steel tank known as a still.

3. Under low pressure, steam is sent into the still and passes through the plant material to be distilled. This causes the aromatic sacs of the plant to burst and isolates the compounds.

4. Aromatic molecules are driven up the distillation apparatus by steam until they reach the swan neck. This steam, laden with essence, travels through a pipe known as a condenser coil which is immersed in a bath of cold water.

5. The steam cools and condenses back into a liquid state, which is collected in adecantation vessel, also known as a Florentine flask or essencier. Floating on the surface of the collected liquid is theessential oil, which is lighter than the water used for its extraction, otherwise known as thehydrosol.

Note: Thehydrodistillation process is almost similar with one difference: initially, the plant material and water are not separated but heated together, directly in the same vessel (still).

Note! The citrus essences such as those of lemon, of the yellow mandarin and green, of lime, bergamot or of the orange are not derived from distillation but from cold mechanical pressing. The essence and water are then simply separated by a cold decantation.

Each essential oil is unique in the sense that its biochemical composition is unlike any other. Aromatherapy can be effective in soothing a variety of ailments.

• Physical Health

  To boost the immune system or improve digestion, certain essential oils can be ingested. However, the use of an essential oil orally always requires prior medical advice. Furthermore, the essential oil must always be diluted and should never be ingested in its pure form. Oral administration is reserved for adults and children over the age of 7. Essential oils should only be taken for short periods, primarily to treat digestive and liver problems. It should be noted that some essential oils, such as peppermint, can also be used by inhalation, especially when one wishes to decongest the nasal passages and overcome a cold.

• Mental Health

  Primarily used in inhalation, certain essential oils are effective in soothing the nervous system and, more specifically, emotional problems associated with feelings of anxiety, fear, and discomfort. They can also promote sleep onset and ensure restorative sleep. The respiratory route is favoured for calming the nerves as the nasal mucous membranes are made up of millions of nerve cells that allow aromatic molecules to diffuse to the brain.

• Dermatology

  Some essential oils are recognised for their moisturising, softening, nourishing, astringent, firming and anti-acne properties. However, caution is advised, applying pure essential oil directly to the skin is not recommended. It is always better to dilute it in a vegetable oil.

  Dosage recommendations vary depending on the essential oils, but generally, it is appropriate to mix 30 drops of essential oil into 50 ml of vegetable oil. The blend can be applied to all parts of the body, avoiding mucous membranes and the eye contour. In local application, this mixture can alleviate various skin problems (acne, redness, dryness...) as well as insect bites, knocks, bruises...

  Caution! Some essential oils are photosensitising and it is advised not to expose oneself to the sun for at least 4 hours after application. Others can cause allergies.Always perform a preliminary test in the crook of your elbow.

  Here is a list of essential oils containing allergenic molecules in significant quantities: aneth, angelica, bergamot, bergaptene-free bergamot, cajeput, cinnamon (bark), lemon, clove, coriander seed, rose geranium, fragrant inula, bay laurel, lemongrass, green mandarin, lemon balm, lemon myrtle, sweet orange, compact oregano, Spanish oregano, palmarosa, grapefruit, turpentine, exotic verbena, fragrant verbena.

• Haircare
  

  Whether it's to combat scalp dandruff, hair loss, excess sebum, or even the dehydration of hair fibres, it can be relevant to incorporate a few drops of a carefully chosen essential oil into one's shampoo and/or hair mask, depending on the issue at hand.

  For instance, to purify the scalp and eliminate dandruff, tea tree essential oil, as well as lavender essential oil and palmarosa essential oil, are recommended.

  As for oily hair, the ones from Rosmarinus officinalis with cineole, fromYlang-Ylang, or even fromSweet Orange Citrus sinensisare more suitable.

  To strengthen one's hair and combat premature hair loss, it is advisable to rely on essential oils that stimulate micro-circulation, such as grapefruit essential oil (Citrus paradisii) or Atlas cedar oil (Cedrus atlantica).

Before using an essential oil, whether externally or internally, it is important to be aware of the following points.

• There are numerous essential oils that contain potentially allergenic or hypersensitising molecules such as limonene, linalool, geraniol or even citrals. Although the risk of allergy depends on one's allergic predisposition, it is essential to perform a skin tolerance test in the crook of the elbow or wrist of the essential oil in question. Furthermore, repeated and prolonged use of the same essential oil promotes an allergic reaction, so remember to take breaks during use.

• Whether taken orally or applied topically, during the first trimester of pregnancy, essential oils should be avoided. Some should be avoided throughout the entire pregnancy, while others can be used after the first 4 months.

• Some essential oils are photosensitising : they make the skin ultra-sensitive to solar radiation, resulting in a skin rash in the form of redness. The photosensitising molecules present in certain essential oils are the coumarins. The following essential oils are not recommended before sun exposure: angelica, bergamot, German chamomile, cinnamon (bark), lemon, sweet fennel, khella, lovage, green mandarin, sweet orange, grapefruit, lemon verbena.

• FAUCON M. Traité d'aromathérapie scientifique et médicale - Les huiles essentielles - Fondements et aides à la prescription (2017).

• Charie, T. Se soigner par les huiles essentielles. Pourquoi et comment ça marche ? Editions du Rocher. (2019).