Olive oil: what are its properties on hair?

Several experimental data suggest that certain compounds in olive oil, particularly oleuropein, could have a positive impact on the hair growth cycle. A study conducted by PARK highlighted that the topical application of oleuropein on mice stimulated their hair growth. This is notably linked to the activation of the Wnt/β-catenin signalling pathway, a key mechanism in regulating the anagen phase, that is, the growth phase of the hair follicle. An increase in the expression of certain genes, such as LEF1 and Cyc-D1, both involved in cell proliferation, was also observed. Finally, an elevation in the levels of the β-catenin protein and the growth factor IGF-1 (Insulin-like Growth Factor 1), which also promotes the survival and activation of follicular cells, was noted.

However, it is crucial to emphasise that these results were obtained following the topical application of pure oleuropein, at a rate of 0.4 mg per day in mice. Olive oil itself contains this molecule, but in much smaller proportions, and its effectiveness as a hair or fur growth activator has not been directly demonstrated. Therefore, additional research would be necessary to determine if the application of olive oil to the scalp could have a similar effect.

Olive oil is rich in fatty acids, including oleic acid, linoleic acid, and palmitic acid. These lipids are particularly beneficial for hair care due to their nourishing and protective properties. Indeed, these fatty acids contribute to the strengthening of the hydrolipidic film that coats the hair fibres, acting as a barrier against external aggressions while limiting water loss. Moreover, thanks to their biomimetic structure, these lipids can insert themselves between the scales of the cuticle, the outer layer of the hair, where they act as an intercellular cement. Oleic acid, in particular, is a major component of the sebum naturally produced by the scalp and is part of the hydrolipidic film. Its presence in olive oil partly explains the latter's good affinity with hair fibres. Thanks to its richness in fatty acids, olive oil reduces hair porosity, making it softer, better hydrated, and more resistant to breakage.

A study by CAMPOS explored the use of vegetable oils as alternatives to silicone found in many hair products. Two vegetable oils were selected for the study: olive oil and Brazil nut oil. The aim was to compare their effectiveness on hydration, nutrition, and strengthening of the hair fibre. The study panelists were divided into 4 groups: a control group, a group with a silicone treatment, a group with Brazil nut oil, and a group with olive oil. The evaluation tests revealed that olive oil allowed for a reduction in combing force and a increase in shine more significant compared to the silicone-based formula. The application of olive oil on the hair would thus result in a general improvement in the condition of the hair.