Understanding Dry Skin

The skin is made up of the dermis, located deep within the skin and the epidermis on the surface. The uppermost part of the epidermis is the stratum corneum which contains the skin’s natural oil layer, known as the lipid bilayer.

The skin has two primary mechanism for controlling its moisture levels. First, the skin’s moisture come from within, rises up through the skin and escapes into the outside air in a process known as transepidermal water loss (TEWL). The lipid bilayer controls how much moisture escapes and how much moisture is held in the skin. Second, the skin produces natural moisturizing factor (NMF) that attracts and binds moisture in its immediate environment, holding moisture in the skin.

Dry skin is caused by external and internal factors.

  • Dry climates cause moisture to be drawn from the skin into the dry outside air.

  • Air conditioners and heaters draw moisture out of the air, creating an artificially dry climate which draws moisture out of the skin.

  • Everyday washing and exposure to harsh detergents cause skin’s lipid bilayer to be stripped, making it easier for moisture to escape from the skin.

  • As the body ages, the skin produces fewer lipids causing the lipid bilayer to thin and making it easier for moisture to escape.

  • Genetics can play a role in the development of dry skin due to naturally occurring lower levels of ceramides in the lipid bilayer.

  • The pH of the skin influences the barrier function. A higher pH level in the skin (caused by shampoos, body washes, etc.) impairs the healthy functioning of the lipid bilayer.

Dry Skin Treatments

There are two principal ways to treat dry skin. The first is to apply an occlusive substance – such as oil, butter or wax – to the surface of the skin to prevent moisture loss. The second is to apply humectant ingredients to the skin that attract and bind water. Of the two ways to remedy dry skin, occlusion is considered the superior option.

How occlusion works – Occlusive ingredients mimic the function of the skin’s lipid bilayer. The best way to understand how occlusion works in dry skin is through an experiment. Take two beakers of water and add oil to one of the beakers. The oil will rise to the top and sit on the surface of the water. Over time, the water in the beaker without the oil will evaporate, while the oil-covered water in the other beaker will stay at the same level.

How humectancy works – Humectant ingredients are used to mimic the function of NMF. Like NMF, humectants attract and bind moisture in their immediate environment, providing skin-hydrating benefits.

Bio-Oil® Dry Skin Gel breakthrough formula is made with 87% oil, 10% humectants and only 3% of water.


Dry Skin Gel