Huile de soja et protection solaire.

Soybean oil for providing UV protection?

Endowed with numerous properties for the skin and hair, soybean oil is used in many cosmetic treatments. Some people even consider it as a natural sun protection. Can this vegetable oil truly be used to protect oneself from UV rays?

What are the effects of UV and sunlight on the skin?

The sun is both beneficial for health and harmful in case of prolonged exposure. Indeed, its rays allow to stimulate the secretion of vitamin D, a pro-hormone that strengthens the immune system, but also to lower blood pressure while ensuring a chrono-biological balance.

However, overexposure leads to undesirable effects on the skin. UV rays promotehyperpigmentation, skin sagging, but can also cause sunburn or skin cancers. These issues are caused by the excessive generation of free radicals, unstable molecules that distort the fatty acids of cell membranes and attack DNA and certain functional proteins such as collagen.

Soybean oil to protect the skin from UV rays?

Thesoybean vegetable oil, also known as "Glycine Soja Oil", appears as a slightly yellowish liquid, highly penetrating, creamy and lightly scented. This oil, usually extracted by cold pressing soybean seeds, is highly valued in cosmetics and is used as a skin conditioning agent, emollient, moisturiser and antioxidant. The properties of the soybean vegetable oil come from its numerous bio-active components.

This natural ingredient also has a photoprotective action. However, it should be noted that this is very limited. Indeed, soybean oil has a SPF (Sun Protection Factor), also known as SPF, of 10. The SPF is the index measuring a skincare product's ability to block UV rays, and therefore to protect the skin from their impact. The higher this index, the greater the photoprotective power. In practical terms, the SPF corresponds to the ratio between the exposure time needed to induce sunburn with and without skincare.

Generally, a sunscreen is considered effective when its SPF (Sun Protection Factor) is 15 or higher. Therefore, applying soybean oil alone is not sufficient to protect against the sun's UV rays, despite the photoprotective properties of this ingredient. Moreover, this vegetable oil is not officially recognised and listed as a sunscreen filter by European regulations. Consequently, its sole use in a sun protection product to provide a sun protection factor is not in compliance with current regulations.

However, the inclusion of soybean oil remains beneficial in sun care products with permitted ultraviolet filters due to its antioxidant properties. These allow it to partially protect the skin by aiding in the fight against accelerated ageing caused by free radicals.

Sun Protection: The Right Practices to Adopt.

To effectively protect oneself from the sun and its dangers, it is recommended to adhere to certain precautionary principles, the first of which is toavoid exposure between 12pm and 4pm, the hours of the day when UV rays are most intense. It is also essential to apply a broad-spectrum sunscreen with a good SPF rating and in sufficient quantity, in order to be well protected.

Finally, dressing appropriately is the best way to protect oneself from the sun's UV rays. The most effective ensemble remains a long-sleeved t-shirt or shirt, long trousers or a skirt made of canvas, a wide-brimmed hat, and sunglasses with protective lenses.

Sources

  • DOWDY J. C. & al. Simplified method to substantiate SPF labeling for sunscreen products. Photodermatology, Photoimmunology and Photomedecine (2003).

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

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