How do natural UV filters work?

Summer is approaching and the sun’s rays are gaining strength. It’s time to start looking for sunscreens that will adequately protect our skin. We are interested in the differences in the effectiveness of classic and natural sunscreens, how to choose sunscreen cosmetics, and what pregnant and lactating women should pay attention to. Dermatologist MUDr. Petra Voitkova.

Natural UV Filters

Madam Doctor, can you describe the difference between chemical and natural sunscreens and how their protective functions work?

All sunscreens contain substances that protect the skin from UVA and UVB rays. Chemical UV filters are molecules that absorb harmful UV rays and convert them into energy in the form of infrared radiation. Examples are aromatic hydrocarbons – aminobenzoates, benzophenones, cinnamates, salicylates, sulfonic acid derivatives – Mexoryl SX and Ensulizol, avobenzone, tinosorb S, and tinosorb M. In contrast, natural or physical UV filters act like a mirror, which means that the rays from the skin only reflect and distract without reacting to them.

Do chemical and natural filter creams provide the same level of sun protection? Could their specific composition have any potential impact on our health?

Creams with a chemical and physical UV filter can provide the same level of UV protection. UV B protection is expressed as an SPF value. If this value is 30 or more, the protection is high enough. If the cream properly protects against UVA rays, it will have a UVA mark on the ring. This means that the sunscreen absorbs 90% of the radiation with a wavelength of 370 nm or more. Of course, the application of the cream must be repeated constantly, because the effectiveness of the cream is reduced by bathing and perspiration. Chemical UV filters often use a combination of several molecules to provide broad-spectrum UV protection. The molecules of old chemical filters can cause contact allergic eczema, are absorbed into the deeper layers of the skin, are often unstable in the light, therefore, it is necessary to repeat the application more often. Fortunately, with the new chemical filters, these negative properties have been completely eliminated.

Naturally, natural sunscreens are more expensive than chemical sunscreens. Could you describe what natural sunscreens are usually made of, what gives them the opportunity, and what affects their price?

Natural mineral UV filters are usually metal oxides. The two most effective of these are used in sunscreens, namely titanium dioxide and zinc oxide. Iron oxides are added to colored day creams and makeup for their color. The effectiveness of metal oxides as UV filters is determined by the size and ideal dispersion of their particles. Titanium dioxide and zinc oxide are both UVA and UVB filtered, but their combination is the most effective broad-spectrum protection. The disadvantage of natural sunscreens is that they leave a white film on the skin. This can be avoided by using optimal particle sizes of 20 to 50 nm, which are not visible on dry skin. Mineral creams with fine titanium dioxide particles have been criticized for their photocatalytic activity, allowing the chemical decomposition of substances by light. In modern sunscreens, this is minimized by coating the surface of the nanoparticles with another layer of another substance. Of course, it should be borne in mind that the technology required to produce a quality cream will also affect its price. We just pay extra for quality.

Doctor, can natural creams provide health or dermatological benefits?

Sunscreens in general, if they are of good quality, slow down the aging of the skin caused by ultraviolet rays (the so-called photoaging – loss of skin elasticity, the appearance of wrinkles, pigmentation, ed.), And reduce the risk of skin tumors, including melanoma. Natural UV filters act immediately upon application to the skin. When using chemical protection creams, it is necessary to wait 30 minutes before the filter starts to perform its function. Likewise, some chemical UV filters, as opposed to physical UV filters, can undergo photodegradation – decomposition by light, so they need to be applied more often than natural creams. Mineral sunscreens are suitable for people with acne or sensitive skin because they do not clog the pores of the sebaceous glands so much and do not irritate the skin.

I want to monitor sensitive skin. For example, should allergy sufferers or people with sensitive skin pay attention to natural sunscreen?

Mineral UV filters have no irritating or allergenic potential. Irritation or contact allergy can occur after natural sunscreen due to hypersensitivity to other ingredients – perfumes, additives, and preservatives.

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