How Do Humectants and Emollients Achieve Moisturising Effects?

To understand the mechanism of moisturisation, one must first learn about the structure of the skin. Being the largest organ of the human body, one of the functions of the skin is to maintain the body's water balance and reduce the loss of moisture. In general, the human skin is made up of three layers, namely epidermis, dermis, and subcutaneous tissue. Meanwhile, keratin, the outermost layer of the epidermis that is often mentioned, is mainly composed of keratinized epidermal cells, lipids, cholesterol, and free fatty acids. It also contains different natural moisturising factors to absorb water and maintain its own moisture. Being the surface layer, keratin does not have its own blood vessel network to supply nutrients and water. Hence, it must depend on the dermis to maintain its needs. In order to acquire sufficient moisture, the skin must be able to absorb and lock moisture at the same time. Both humectants and emollients have played these two important roles:

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  • Humectants: increase the humidity of the epidermis of the skin. Their function is similar to the natural moisturising factors in the keratin. After the humectants are absorbed, they can stay in the keratin for a period of time and absorb the necessary water from the lower layer of the skin and maintain sufficient moisture in the epidermal layer. Some common humectants include glycerine, propylene glycol, urea, hyaluronic acid, etc.
  • Emollients: lubricate and soften the skin while preventing water evaporation and loss. It is important to bear in mind that the loss of moisture content in the skin is mainly through transepidermal water loss (TEWL). This principle, which works like a layer of oil in a bowl of hot soup that greatly reduces the evaporation rate of water, highlights the importance of the fatty substance in the keratin.; Some common emollients include olive oil, cocoa oil, mineral oil, petroleum jelly, beeswax, etc.
Tips for Choosing the Moisturising Products

Last but not the least, reading the ingredient list is the key to choosing the moisturising products suitable for your skin. Since the ingredients of cosmetics are arranged according to content levels from the highest to lowest, water is always the first or second ingredient to be mentioned. You can choose the right product according to the skin's oil content and need for moisturisation. For skin types that are particularly dry, choose products that contain more emollients. On the contrary, choose products with more moisturisers and avoid emollients for oilier skin types. Click here to find out the moisturizer cream could help your keep moisturised.

Last Updated: Aug 2020
Please note that all medical health articles featured on our website have been reviewed by Quality Healthcare doctors. The articles are for general information only and are not medical opinions nor should the contents be used to replace the need for personal consultation with a qualified health professional on the reader’s medical condition.