According to a new study by the UC San Francisco dermatology professor Peter Elias, MD, moisturizers and other products may be doing as much harm as good, especially for people with sensitive skin.
He said, “The skin – bombarded daily by our exposure to things that include sunlight and environmental toxins – is highly effective and enduring in its role as a barrier. That barrier is similar to the brick wall.”
In 1980, he developed a model of the skin called corneocytes, composed of dead cells that make up the surface of the skin. Those cells are bricks encompassed and held together by membrane sheaths made of a “mortar” of three lipids: cholesterol, ceramides and fatty acids.
Elias said, “What’s important is that those three lipids are present at approximately equal ratios, equal numbers of molecules of each of them. When that ratio gets thrown off, he says, the membrane sheaths don’t completely fill the spaces between the cells.”
“Then, instead of a brick wall, you get this Swiss cheese, which is not what you want.”
During his dermatology practice, Elias’ patients acknowledged that moisturizers provided short-term relief, but in the long term, their skin would feel drier.
Luckily for individuals with skin conditions, Elias is getting a more clear picture of what the issue is. Sadly, he found out from an ongoing investigation of moisturizers doing more damage than anything else for certain people.
Elias said, “That’s because maintaining the brick wall comes down to a suite of related factors: pH of the skin, the makeup of the ‘mortar,’ and the body’s response to the ‘Swiss cheese’ situation.”
“Most common moisturizers are designed to provide a layer that keeps skin from getting too dry, which is fine for normal skin. But these lotions may lack ‘mortar’ ingredients, contain them in the wrong proportions, or change the skin’s naturally acidic pH.”
The study revealed that the enzymes responsible for producing ingredients for the mortar work best at this acidic pH. When the pH is thrown off, there isn’t enough mortar produced, or the three lipids aren’t produced in the right ratios. The result is a naturally occurring “Swiss cheese” that gives rise to skin conditions such as eczema.
Elias explained, “The body perceives the ‘Swiss cheese’ as an injury, and in response produces cytokines, small molecules that trigger the inflammation response that leads to healing. But in people with sensitive skin or skin conditions, their repair machinery – the enzymes that make the three lipids – aren’t functioning properly. So the injury remains and the cytokines keep coming, causing greater inflammation and irritation.”
He further added, “We found that the great majority of moisturizers haven’t been tested on people with sensitive skin. Adding a moisturizer that doesn’t supply the correct ratio of lipids or throws off the pH can simply exacerbate the situation and increase inflammation.”
“It induces a vicious cycle where the patient is applying material frequently for temporary relief but the result is a long-term worsening of the skin.”
Mao-Qiang Man, MD, also a research scientist with the San Francisco Veterans Administration (VA) Health Care System-affiliated Northern California Institute for Research and Education said, “The key for people with sensitive skin may lie in a lotion that is formulated for skin repair and contains the “mortar ingredients” in their proper proportions.”
Elias and Mao-Qiang are now planning for two larger-scale studies in China where they will compare the effect of a lotion designed for barrier repair on cytokines in the blood with that of other off-the-shelf moisturizers. They will also observe how much of the body needs to be covered regularly with the barrier repair formula for it to be effective.
The notion that repairing the “brick wall” could lead to these kinds of whole-body benefits is a relatively new one. Elias believes that for a long time, the barrier function of the skin has been underappreciated because it fulfills its role so well.