Zinc oxide

It is produced by burning zinc vapour in a stream of air. When exposed to air, it absorbs moisture and carbon dioxide and turns into zinc oxide. Zinc is a soft metal with a low melting point. It has been used since the Middle Ages, and its presence in the diet is essential for the proper development of the body. It is relatively abundant in the Earth's crust, with an average content of approximately 100 mg/kg. Its concentration in seawater is also quite high – 0,01 milligrams per litre. The main zinc mineral is zincite. An odourless white powder with the chemical formula ZnO, it may look unassuming, but it has a wide range of uses in natural cosmetics. It is an active ingredient in deodorants and an antiseptic, antibacterial protective agent for acne or irritation on babies' bottoms or feet. Zinc has antibacterial properties, reduces inflammation and can curb the excessive sebum production that causes acne. In deodorants, it absorbs excess moisture, but most importantly, its antibacterial action prevents bacteria from breaking down and multiplying, and from breaking down sweat, which is the main cause of odour. Zinc oxide does not penetrate the skin; it stays on the surface, forming a protective barrier.

Zinc oxide restores the skin barrier by forming a physical protective layer on the skin's surface, preventing harmful substances and UV radiation from penetrating. It acts as a broad-spectrum mineral UV filter, reflecting both UVA and UVB rays like a mirror to provide photostable protection without losing effectiveness. It has antibacterial properties, binding to proteins in the cell membranes of bacteria such as staphylococci and E. coli and disrupting their permeability. It soothes inflammation, supports wound healing and absorbs excess moisture. In deodorants, it regulates sebum production and suppresses odour. Recommended concentrations: 2-10 % in emulsions, 1-60 % in mineral cosmetics, typically 15-25 % in sunscreens for SPF protection.

It is recommended for sensitive, dry, oily, acne-prone, dehydrated and mature skin. It is ideal for children with nappy rash, people with atopic eczema, and acne-prone skin to reduce inflammation and excess sebum production. It is suitable for people with sensitive skin looking for natural UV protection without chemical filters, including pregnant women and allergy sufferers. In mineral make-up, it mattifies the skin and covers imperfections. Avoid nanoparticles due to potential risks; opt for microparticles that do not leave a white cast.

A study by Dunford et al. (1997) showed that zinc oxide nanoparticles generate reactive oxygen species under UV radiation, damaging the DNA of skin cells. A study by Sharma et al. (2009) confirmed that ZnO and TiO2 nanoparticles react with UV radiation and cause damage to skin cells. An official study of ALPHANOVA products demonstrated that mineral filters, including ZnO, remain on the skin's surface and do not penetrate the barrier.