Castor oil to get rid of brown spots on the face?

Brown spots, as their name suggests, are dark-coloured patches that appear on the skin due to hyperpigmentation. This condition is characterised by an excessive stimulation of melanocytes, the cells responsible for producing melanin during the process of melanogenesis. Several factors can trigger brown spots, including repeated and prolonged exposure to the sun, oxidative stress or hormonal fluctuations (pregnancy, menopause...). Pigmented spots frequently appear around the age of forty, but they can also emerge earlier.

Even though pigmentation spots pose no health risk, some individuals choose to eliminate them. Beyond laser treatments and dermatological peels, there are cosmetic actives capable of reducing hyperpigmentation. As for the castor oil, some scientific studies suggest that it could help lighten the skin. Notably, a recent clinical trial involving 22 individuals with pigmented dark circles can be cited. These volunteers applied a cream containing 10% castor oil to their dark circles twice a day for two months. At the end of the study, an average pigmentation improvement of 8.2% was measured, while no side effects were reported.

Castor oil appears to have the ability to somewhat diminish brown spots.

Scientists have hypothesised that castor oil could inhibit the activity of tyrosinase, the enzyme that allows the conversion of tyrosine into melanin during melanogenesis. This hypothesis was supported during an in vitro study conducted by another group of researchers. These researchers focused on the anti-tyrosinase activity of an aqueous extract of the castor plant. According to their findings, the aqueous extract was able to inhibit 88.98% of the tyrosinase activity of a fungus. However, the concentration that allowed such inhibition was not disclosed. Moreover, the study was conducted on an aqueous extract of the castor plant, not on castor vegetable oil. Even though these two ingredients have similarities, they are not identical in every aspect. Therefore, while this study is a first step towards elucidating the potential depigmenting properties of castor oil, further research is still necessary.