What are the benefits of rosemary essential oil for the skin?

Rosemary essential oil is composed of a blend of terpenes, including eucalyptol, which is renowned for its anti-inflammatory properties. A study conducted on rats revealed that eucalyptol significantly inhibited 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, particularly TNF-α, IL-1β, and IL-6, play a role as pro-inflammatory mediators in the inflammatory process.

Furthermore, the α-pinene and borneol, found in rosemary essential oil, also contribute to its anti-inflammatory activity. 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.

Rosemary essential oil possesses antioxidant properties that may be beneficial for combating oxidative stress. This property aids in the fight against the body's production of free radicals. Indeed, 1,8-cineole, α-pinene, and β-pinene are three components of this essential oil that have a free radical scavenging activity. Their role is to combat free radicals, which are unstable molecules with a free electron. As a reminder, they are responsible for the degradation of skin cell constituents such as the elastin and the collagen. The result is a loss of elasticity, typically manifesting as premature cell ageing and the appearance of wrinkles. The active ingredients in rosemary essential oil neutralise free radicals by donating an electron to them.

Furthermore, the role of antioxidants is to form a protective barrier on the skin's surface to shield it and prevent oxidative stress. This phenomenon equates to an excessive multiplication of free radicals following external aggression (exposure to UV rays, pollution, etc.).

Numerous studies have been conducted to assess the antibacterial activity of rosemary essential oil. These researches have demonstrated that this oil exhibits inhibitory activity against the growth of certain bacteria such as Escherichia coli and Propionibacterium acnes, a bacterium that is present in larger quantities during acne.

The inhibitory effect of rosemary is the result of the action of 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 cell membrane, causing changes to genetic material and nutrients, altering electron transport and the leakage of cellular components. Additionally, they produce an interaction with the protein membrane which results in the loss of membrane functionality and structure. Other studies have also shown that camphor and borneol present in the essential oil inhibit Gram-positive bacteria by inducing changes in bacterial metabolism. However, specific information on this topic is limited.

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

Some sources suggest that rosemary essential oil may have astringent properties, which could help to tighten the skin's pores, reducing the likelihood of hair follicles becoming blocked by sebum, which can lead to the formation of comedones (blackheads) and spots.

It is, however, important to note that to date, no scientific study has demonstrated that the application of rosemary essential oil has visible beneficial effects on the occurrence of comedones or pimples.