Castor oil for hydrating dry skin?

Relatively thin, dry skin is characterised by limited elasticity and a high sensitivity to temperature changes. To the touch, dry skin often feels rough and tends to flake. Unlike dehydrated skin, dry skin is not lacking in water but in fat. This is due to a low production of sebum, one of the components of the hydrolipidic film. Dry skin lacks lipids, which makes the epidermis more susceptible to external aggressions and facilitates the evaporation of the water contained in the skin. The lack of flexibility and the significant fragility of dry skin makes it particularly prone to skin ageing.

Dry skin requires a tailored skincare routine, incorporating moisturising and nourishing ingredients, such as castor oil. Capable of strengthening the hydrolipidic film, it is indeed beneficial for dry skin. According to a study on skin explants, castor oil could reduce transepidermal water loss (TEWL). Indeed, an hour after application, a difference of 50 µg/cm2.h was observed between the skin on which castor oil was used and the one that received nothing. This difference was 40 µg/cm2.h after 24 hours. It thus appears that the topical application of castor oil significantly reduced water loss.

The hydrating and nourishing effects of the castor oil were also evaluated during a clinical trial involving 15 individuals with dry skin. Each volunteer was given a formulation based on castor oil and distilled water. A bioelectrical impedance analysis was used to provide numerical values representing the skin's moisture levels. According to the model used, a rate below 33% indicates very dry skin, a rate between 34% and 37% indicates dry skin, a rate between 38% and 42% signifies normal skin, and a rate above 43% shows hydrated skin. The results obtained ten days later are transcribed in the table below.