How can castor oil support nail health?

Castor oil is a vegetable oil obtained by cold pressing the seeds of the common castor plant, a shrub of the Euphorbiaceae family. Used in personal care, castor oil is a viscous liquid with an oily texture, a clear to yellow colour and a subtle odour. It is noted for its potential effect on the growth of hair, but it offers various benefits for the hair, as well as for eyebrows, eyelashes, the beard and the skin. Hydrating, nourishing, soothing and antibacterial, castor oil is a vegetable oil valued in personal care for its versatility.

Castor oil is valued for nail care. However, to date no scientific study has demonstrated its benefits for nails.

Despite the lack of clinical studies, several factors suggest that regular use of castor oil on nails and cuticles could strengthen them:

• Castor oil to fortify nails.

  Castor oil is valued for its ability to reinforce nail structure. It penetrates keratin, fills microcracks, and improves cohesion among layers, reducing nail fragility. Castor oil could therefore strengthen the nail plate and prevent brittle nails, ridged or damaged nails. Moreover, a study in vitro showed that castor oil could stimulate keratin production in hair follicles, promoting hair strength and resilience. By cautious extrapolation, it could also support keratin synthesis in nails, although this requires confirmation.

• Castor oil to help prevent fungal infections of the hands and feet.

  Castor oil also has antifungal properties. Ricinoleic acid, its main fatty acid, exerts an inhibitory effect on the growth of certain fungi responsible for nail fungal infections, such as Cunninghamella bertholletiae. A study compared castor oil’s activity with standard antifungal agents using disc diffusion and minimum inhibitory concentration (MIC) tests. Results showed castor oil yielded a slightly larger mean inhibition zone (22.44 mm) than amphotericin B (20.66 mm), with a similar MIC (1.72 µg/ml versus 1.66 µg/ml). These findings suggest castor oil could help limit nail fungal infections, although clinical studies would be needed to confirm this.

• Castor oil to hydrate nails and cuticles.

  The cuticle is the small piece of skin surrounding the nail on hands and feet, and it covers and protects its base. It acts as a primary barrier against external stressors and infections. Due to its rich fatty acid content, castor oil helps hydrate this neglected area and prevents cracking. By hydrating the nails, this plant oil increases shine.

• Castor oil to protect nails from oxidation.

  In addition to its high fatty acid content, castor oil also contains vitamin E, a potent natural antioxidant. This vitamin helps neutralise free radicals generated by repeated exposure to external stressors such as UV rays, pollution, or chemical agents found in detergents. Castor oil thus helps limit lipid oxidation in nail keratin, helping preserve their structure, strength, and colour. Oxidative stress can dull nails, giving them a yellowed appearance.

• Castor oil to stimulate nail growth.

  Castor oil is also presented as a solution to stimulate nail growth. However, to date no scientific study has established a link between applying castor oil and accelerated nail growth. It may be assumed that by hydrating the nails, nourishing them and strengthening the nail plate, castor oil creates favourable conditions for their growth and limits their breakage.