Soybean oil for skin lightening?

Extracted from soybean seeds through cold pressing, soybean vegetable oil is used in the composition of many cosmetic products as a skin conditioning agent, emollient, moisturiser and antioxidant. The properties of this botanical extract however, go further. Indeed, several studies have shown that soybean oil helps to prevent and reduce the appearance of pigmentation spots. It can thus be used to even out the complexion and restore its radiance.

Firstly, soybean oil possesses a significant antioxidant activity that is beneficial in preventing hyperpigmentation. Indeed, its vitamin E content allows it to protect the skin from oxidative stress, particularly caused by UV rays from the sun and exposure to tobacco or pollution. Vitamin E neutralises free radicals before they can attack cellular components. More specifically, the free hydroxyl function carried by the aromatic cycle of this compound reacts with the free radicals and provides the missing electron, which helps to stabilise them.

Furthermore, soybean oil operates through various mechanisms to regulate melanogenesis, the process of melanin synthesis. Firstly, we can mention the action of fatty acids, its major compounds. These inhibit the activation of the PAR-2 receptor, thereby causing a decrease in the phagocytosis of melanosomes by keratinocytes, the cells of the horny layer. The transfer of melanin is then inhibited, thereby preventing the skin pigmentation process. Soybean oil also inhibits the activity of dopa-oxidase, an enzyme catalysing the oxidation of dihydroxyphenylalanine acid into dopachrome, one of the precursors of melanin.

The brightening effect of soybean oil has been demonstrated in vivo in a study involving 65 participants with moderate facial photodamage. For 12 weeks, the participants applied a soybean oil-based cream to their faces daily. The effectiveness was monitored through clinical observation, self-assessment, colourimetric evaluations, and digital photography. The results showed that this cream had significantly improved the skin's complexion by reducing its pigmentation.

• LEYDEN J. & al. Efficacy of a soy moisturizer in photoaging: a double-blind, vehicle-controlled, 12-week study. Journal of drugs in dermatology (2007).

• VIJAY K. & al. Cosmeceuticals for Hyperpigmentation What is Available? Journal of Cutaneous and Aesthetic Surgery (2013).

• MURTAZA G. & al. Dermatological and cosmeceutical benefits of Glycine max (soybean) and its active components. Acta Polonia Pharmaceutica (2015).