Rosemary Essential Oil: What should you know?

Rosemary, originating from the Mediterranean region, presents itself as a small, robust shrub, dense and with evergreen foliage. Its leaves, which resemble needles, maintain their greenery throughout the year. Since antiquity, rosemary has been revered as a sacred plant, carrying symbols of love and being nicknamed the Rose of Mary or the Herb of Crowns. It has been used to weave crowns for various wedding ceremonies.

Theessential oil of rosemary is one of the most popular and widely used essential oils in aromatherapy due to its numerous health and wellness benefits. It can be used to promote focus and mental clarity. In aromatherapy, it is often used to help alleviate stress, anxiety, and mental fatigue. It is extensively used to relieve rheumatic pains, stimulate blood circulation, and soothe digestive disorders.

The essential oil of rosemary has a specific composition with numerous active molecules that contribute to the many benefits it brings to the skin. The table below lists the different molecules present in rosemary essential oil and their main associated properties.

The essential oil of rosemary is obtained through steam distillation of the aerial parts of the rosemary plant, Rosmarinus officinalis. The aerial part in question is the summits, that is, the end of the stem.

The plants are harvested and then placed into a still, a distillation device specifically designed to extract essential oils. Steam heats the rosemary, enabling the extraction of its active molecules. The steam, now laden with essential oils, then passes through a cooling system where it condenses into a mixture of water and oil. This liquid phase is then separated into two parts due to their densities: the essential oil, which is above the water, is collected. The rosemary essential oil is then filtered to remove any impurities, resulting in a pure and concentrated quality oil.

Note: It requires approximately 50kg of rosemary to produce 1kg of rosemary essential oil.

The essential oil of rosemary possesses numerous properties that are the source of many skin benefits.

• Anti-inflammatory.

  Rosemary essential oil is a blend of terpenes, of which eucalyptol is particularly recognised for its anti-inflammatory properties. A study conducted on rats demonstrated that eucalyptol significantly reduced the production of cytokines, such as TNF-α, IL-1β, IL-4, and IL-5 in lymphocytes, as well as TNF-α, IL-1β, IL-6, and IL-8 in monocytes. These cytokines, notably TNF-α, IL-1β, and IL-6, are known to be pro-inflammatory mediators in the inflammatory process.

  Furthermore, rosemary essential oil contains α-pinene and borneol, which also contribute to its anti-inflammatory action. The α-pinene works by inhibiting the nuclear translocation of NF-kappa B and reducing inflammatory markers, while borneol suppresses the expression of pro-inflammatory cytokines.

  By inhibiting these pro-inflammatory cytokines, rosemary essential oil helps to reduce inflammation and can therefore be beneficial in alleviating symptoms associated with inflammatory issues such as arthritis, muscle pain, joint pain and skin conditions like theacne or the psoriasis.

• Antioxidant.

  Rosemary essential oil exhibits antioxidant properties that are particularly beneficial in combating oxidative stress. These properties serve to counteract the production of free radicals within the body. Among the key components of this essential oil, 1,8-cineole, α-pinene, and β-pinene play a crucial role by acting as free radical scavengers. Free radicals are unstable molecules equipped with a free electron, responsible for the degradation of skin cell constituents, such as elastin and collagen. This can lead to a loss of skin elasticity, typically resulting in premature cell ageing and the emergence of wrinkles. They are also responsible for the degradation of melanin in hair, causing the onset of grey hair.

  The compounds found in rosemary essential oil neutralise free radicals by donating an electron, thereby helping to maintain skin health. By forming a protective barrier on the skin's surface, the antioxidants in the essential oil help to shield the skin from oxidative stress, which can result from exposure to UV rays, pollution, or other external aggressors. Thus, rosemary essential oil prevents premature skin ageing.

• Antibacterial.

  Studies have revealed that this oil exhibits inhibitory activity against the growth of certain bacteria, such asEscherichia coli and Propionibacterium acnes, a bacterium that proliferates abundantly in cases of acne.

  This inhibitory effect of rosemary is attributed to the action of several compounds, including rosmarinic acid, rosmaridiphenol, carnosol, epirosmanol, carnosic acid, rosmanol, and isorosmanol. These compounds can hinder the growth and multiplication of bacteria by disrupting their metabolism. They interact with the cellular membrane, causing alterations in the genetic material and nutrients, disrupting electron transport and leading to the leakage of cellular components. Furthermore, they interact with membrane proteins, resulting in a loss of membrane functionality and structure.

  Other studies have also demonstrated that camphor and borneol, found in rosemary essential oil, inhibit Gram-positive bacteria by inducing changes in their metabolism. However, specific information on this subject is still limited.

  Thus, rosemary essential oil can be utilised in skincare formulations to help treat skin conditions caused by bacteria, such as theacne and other skin infections.

• Astringent.

  Some studies suggest that rosemary essential oil possesses astringent properties, which could help to tighten skin pores and potentially reduce the risk of hair follicle blockage by sebum, responsible for the appearance of comedones (blackheads) and pimples. However, it is important to note that to date, no scientific study has provided conclusive evidence of visible beneficial effects from the application of rosemary essential oil on the appearance of comedones or pimples.

The essential oil of rosemary is contraindicated during pregnancy and breastfeeding, and in children under the age of 6, as some substances it contains could be harmful to the development of the foetus or infant.

Avoid contact with mucous membranes as this could cause irritation. If you are taking medication, consult a healthcare professional before using essential oils to ensure there are no risks of unwanted interactions.

The essential oil of rosemary can trigger allergic reactions in some individuals. Therefore, it is recommended to perform a preliminary skin test on a small area to check for tolerance before application. Moreover, never use this essential oil in its pure form as it could cause skin irritations.

Rosemary essential oil is found in various skincare products in the form of cream, gel, lotion, shampoo, etc. It is incorporated at a concentration of around 0.4 to 0.6% of the total formula. Notably, it is one of the active ingredients used in Typology's densifying shampoo. Combined with ingredients such as almond proteins and biotin, it densifies the hair, hydrates and soothes the scalp.

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JIANG Y. & al. Chemical composition and antimicrobial activity of the essential oil of Rosemary. Environmental Toxicology and Pharmacology (2011).

BHOWAL M. & al. Eucalyptol: Safety and Pharmacological Profile. Journal of Pharmaceutical Sciences (2015).

HAMIDPOUR S. & al. Rosmarinus Officinalis (Rosemary): A Novel Therapeutic Agent for Antioxidant, Antimicrobial, Anticancer, Antidiabetic, Antidepressant, Neuroprotective, AntiInflammatory, and Anti-Obesity Treatment. Biomedical Journal of Scientific & Technical Research (2017).

EL HACHLAFI N. & al. In Vitro and in Vivo Biological Investigations of Camphene and Its Mechanism Insights: A Review. Food Reviews International (2021).

KHARAZMKIA A. & al. Potential effects of alpha-pinene, a monoterpene commonly found in essential oils against Toxoplasma gondii infection; an in vitro and in vivo study. Journal of Parasitic Diseases (2022).