Which of the following was introduced in the twentieth century related to skincare?

Alpha hydroxy acids (AHAs) were introduced in the twentieth century as a significant advancement in skincare formulations. They are derived from natural sources like fruits and milk and have been extensively researched and developed for their exfoliating properties. AHAs are used to improve skin texture, reduce the appearance of fine lines and wrinkles, and promote cell turnover. Their introduction led to a broader understanding of chemical exfoliation in skincare, marking a shift from physical exfoliation methods.

This innovation reflects the ongoing evolution of skincare science and the emphasis on using ingredients that can effectively enhance skin health and appearance. The development of AHAs opened up new formulations and approaches in the cosmetic industry, making them a pivotal discovery in the realm of skincare during that time.