Thermal water to combat dull complexion?

According to the Ministry of Labour, Health, Solidarity and Families, thermal water is a natural mineral water used for therapeutic purposes. To clarify, a natural mineral water is a microbiologically safe water originating from an aquifer or underground deposit exploited from one or more natural or drilled emergences constituting the source. Thermal waters have been the subject of scientific research and their use is regulated in thermal centres or in cosmetics. There are several types of thermal waters, depending on their chemical composition. Those frequently used in dermatology and cosmetics are bicarbonate waters and oligo-metallic waters. They are primarily used for their soothing, anti-inflammatory and healing properties, particularly beneficial for sensitive skin.

Thermal waters could also have a beneficial effect on the complexion and help to brighten the skin. This is at least what is suggested by research conducted on a serum composed of 89% thermal water from the volcanic region of Auvergne. Studies in vitro indicate that this treatment protects the integrity of the skin barrier by stimulating the expression of certain endogenous enzymes, such as catalase, superoxide dismutase and glutathione peroxidase, thereby strengthening the skin's antioxidant defences.

This antioxidant property is particularly beneficial in combating dull complexion. Indeed, free radicals, unstable molecules produced in excess during oxidative stress, can damage various skin organelles, including keratinocytes, the cells that make up the epidermis. Free radicals can notably alter the DNA and mitochondrial activity of keratinocytes, thereby disrupting their ability to proliferate and potentially leading to a slowdown in cellular renewal. This slowdown results in an accumulation of dead cells on the skin's surface, forming a thick and irregular horny layer. This agglomeration prevents light from reflecting properly on the skin, giving it a dull and tired appearance.

By enhancing the skin's antioxidant capacity, thermal water could potentially help combat the dull complexion.

A clinical study, conducted with 52 women with dull complexions, confirmed the benefits of this thermal water-based serum in restoring skin radiance. The treatment was applied twice daily to cleansed, dry skin over a four-week period. At the end of this period, a visual evaluation by dermatologists concluded in a significant improvement in skin radiance. Similar results were obtained through self-assessment by the volunteers. Furthermore, no irritation or side effects were observed over the 28 days.

These promising results, however, should be interpreted with caution. The study mentioned above focused on a serum, indeed composed of 89% thermal water, but also containing other active ingredients, such as the hyaluronic acid, the percentage of which was not disclosed. This latter is known for its moisturising and plumping properties, which can also contribute to reviving the complexion's radiance. There is thus an uncertainty about the exact role played by the thermal water. The lack of comparison with a formula without thermal water or with thermal water limits the conclusions. Moreover, this clinical study is, to date, one of the only ones to have evaluated the effects of thermal water on dull complexion. It is therefore difficult to draw solid conclusions from it. Finally, one may question the generalisation of these results in specific contexts, such as dull complexions linked to atmospheric pollution or a lack of sleep.

Further studies are still required to assess the ability of thermal water to combat dull complexion.