Black seed oil to combat dark spots?

The pigmentation spots are the result of an accumulation of melanin in the skin. As a reminder, melanin is a brown pigment that plays a protective role against UV rays. However, in the event of overproduction, pigmentation spots impacting the uniformity of the complexion appear. Depending on their origin, these are classified into three distinct categories.

• The sun spots caused by prolonged and repeated exposure to the sun's UV rays.

  The primary cause of the appearance of brown spots is exposure to the sun's UV rays. Indeed, these activate the melanogenesisprocess, which is the synthesis of melanin. Sun spots gradually form throughout life, as exposure to the sun is repeated. That's why it's important to apply a sunscreendaily. Tobacco or pollution can also play a role in their appearance, as these elements generate oxidative stress in cells and accelerate skin ageing.

• The pregnancy mask is linked to hormonal changes.

  Pregnancy is not without its hormonal consequences. It notably leads to a significant increase in the levels of oestrogen and progesterone in the body, hormones capable of activating melanogenesis. Also known as melasma, the pregnancy mask can also appear following the use of a contraceptive pill or hormone replacement therapy.

• Thepost-inflammatory hyperpigmentation.

  Brown spots can ultimately form as a result of skin inflammation or lesions. Indeed, during inflammation (acne, burn, injury...), pro-inflammatory cytokines stimulate the activity of melanocytes.

Theblack seed oil is a natural ingredient derived from the seeds of black cumin. Versatile, it is used for both its gastronomic and cosmetic properties. It can be found in the INCI list of many skin care and hair care products under the name Nigella Sativa Seed Oil due to its numerous virtues: anti-inflammatory, antioxidant, healing, moisturising... Sometimes, black seed oil is also attributed with a lightening action.

Nevertheless, no scientific study has to date demonstrated that this ingredient has effects on brown spots. On the contrary, there are reasons to believe that black seed oil could instead be useful in cases of hypopigmentation or vitiligo. In an in vitro study, researchers incubated wall lizard skin in solutions with different concentrations of thymoquinone, one of the active ingredients of black seed oil. This species of lizard was chosen because its pigment response is uniform.

After incubation for about ten minutes, a dispersion of melanophores was observed. Melanophores are cells specific to certain amphibians and birds that can be considered analogous to mammalian melanocytes. However, unlike melanocytes, melanophores do not synthesise melanin, they merely store it. Melanophores can be dispersed in the cytoplasm, which is then darkened, or gathered into clusters (clear cytoplasm). Thus, the dispersion of melanophores observed in the study is synonymous with a darkening of the skin.

Black seed oil cannot, at this point, be considered as a lightening ingredient and instead appears to have a potential darkening effect. If you wish to diminish your brown spots, we would rather recommend the vitamin C, the azelaic acid, the arbutin acid, the liquorice extract, the tranexamic acid or even the glycolic acid.

• MEITEI K. & al. Nigella sativa seed extract and its bioactive compound thymoquinone: the new melanogens causing hyperpigmentation in the wall lizard melanophores. The journal of pharmacy and pharmacology (2011).

• KIM B. & al. Black Cumin ( Nigella sativa L.): A Comprehensive Review on Phytochemistry, Health Benefits, Molecular Pharmacology, and Safety. Nutrients (2021).