Features

Allergies, atopic dermatitis and the importance of correct skincare

10 October 2010

In a background of rising allergic diseases, it is worth examining how healthy skin can be compromised. Just as important is an understanding of the effect on skin of cleansers, and how to choose a mild product that is appropriate for baby skin.

Baby allergies

Key points

  • Allergic diseases are on the rise
  • Both genetics and the environment play a role in the rise of allergic disease
  • Contaminants can pass through a damaged skin barrier
  • Using specifically designed skin cleaning products protects the infact skin barrier
  • A cleanser for infant skin should be mild but be able to remove both water and fat-soluble impurities
  • Specially-designed cleansers intended for baby skin utilise large micelle technology to be mild and avoid technology to be mild and avoid compromising the skin barrier

Background 

Allergic diseases are an increasing problem, both in the industrialised world and in developing countries. In many industrialised countries, approximately one third of the population become affected by allergic disease at some point in their lives." The prevalence of atopic dermatitis (AD) has been steadily increasing since 1945 around the world. For children, in particular, the prevalence has increased from 4% to 5% in the 1940s to greater than 25% today.  

There are many theories about why atopic diseases are becoming increasingly problematic. These theories can be divided into two main hypotheses. One is that new risk factors connected to nutrition, environmental factors or lifestyle have affected the development of allergic diseases among the population. The second hypothesis is that protective factors connected to how people once lived have been lost, resulting in an increased vulnerability to the development of allergic diseases."

Despite intensive, worldwide research, it's difficult to determine the connection of causes and a lot of the research is hypothesis generating. However, scientists agree that the background of allergic diseases is multifactorial. There is a strong consensus that heredity plays an important role. If a child has one parent with AD then they have a 20% chance of developing AD, but if both parents have/ had AD, the risk increases to 50%.

Beyond genetic factors, the environment also plays an important role in the development of allergic diseases and AD. The sensitivity of the skin barrier to damage by environmental agents and harsh surfactants has also been on the rise for the past 50 years. Products can have a positive or a negative effect on the skin barrier. This is why it's important to understand how environmental agents and surfactants affect the skin and therefore choose products appropriately.


What causes skin barrier disruption?

Healthy skin is soft, smooth and flexible. But various environmental agents such as excess water, hard water, alkaline soap, inappropriate detergents and other substances can threaten healthy skin by increasing protease activity. Although these enzymes are natural and needed for the exfoliation of skin cells, if their activity is increased beyond normal levels, they can wear down the skin barrier. This can sometimes lead to disruption of the skin barrier. When the barrier is compromised, contaminants can enter and cause inflammation, allergies and other disease.

AD is a chronic inflammatory skin disease associated with cutaneous hyper-reactivity to environmental triggers that are not offensive to normal, non-atopic individuals." AD is of multifactorial origin and arises as a result of the interaction of many genes with environmental factors." Heredity is a strong indication when predicting the likelihood of an infant developing AD

A baby is more at-risk when genetically pre-disposed. But, preventing AD may be possible. There exists a window of opportunity in the first few months after birth to change the environment to prevent the development of AD. Preventing the development of AD may be possible by taking special care of baby skin from birth." Everything that is used on a baby's skin from birth should be designed to enhance the skin barrier rather than damage it. Wash products should strike the ideal balance between cleansing efficacy and their effect on the integrity of baby skin. The ideal properties of a baby wash product should respect the natural pH of the stratum corneum (SC), effectively cleanse without damaging the SC, respect skin hydration levels and prove to be cosmetically acceptable.1° Not all cleansing products are appropriate for baby skincare and cleansers not specially formulated for infant care should be avoided (See Box 1).

Although water does hydrate the skin, the effect is temporary, lasting only about 30 seconds. Once the water evaporates, skin begins to dry. Water alone bathing can increase TEWL and surface irritation, while also damaging the skin. It also has no buffering capacity which can cause skin pH levels to rise, leading to enhanced protease activity and skin barrier breakdown.

A complete baby skincare regimen involves optimally formulated products to enhance the skin barrier. In a recent clinical study on baby skincare regimens, Garcia-Bartels et al investigated the long-term effect of specially formulated baby products twice-weekly on skin barrier in newborns. They found that the skin barrier develops either better or equally using a twice-weekly skincare regimen compared to bathing with water alone."


Box 1: what makes a cleanser mild?

A mild cleanser is one that successfully removes impurities (water-soluble and fat-soluble impurities) yet does not harm or weaken the skin barrier, as measured in certain assessments such as TEWL or erythema measurements, or clinically observable signs such as dryness, itchiness, redness.

Water alone is not an effective cleanser for baby skin as it cannot remove all of the impurities found on baby skin. Therefore, for hygienic purposes, it is recommended to use a cleanser, or a surfactant, on baby skin. However, not all cleansers are alike. There is a difference in mildness.

Because surfactants have both hydrophobic and hydrophilic properties, they form sphere-like structures in solution, called micelles. Micelles can interact and disrupt the skin structure, reducing barrier function.' The smaller the micelle is, the greater the risk of it penetrating and irritating the skin barrier. Therefore, a mild cleanser should be comprised of micelles that are large in size.' This can be achieved by modulating the proportion of surfactant types.

The effect of micelle size on cleanser mildness
Figure 4: The effect of micelle size on cleanser mildness

 

The importance of micelle size

Cleansers contain surfactants which remove fat-soluble impurities from the skin. In solution, surfactants form micelles; cleansers containing large micelles are mild and less likely to penetrate the skin. The result is that different surfactant formulations have different levels of mildness. Figure 4 illustrates how mildness increases with micelle size in cleansers.

As infant skin continues to develop through the first year of life, it requires gentler cleansing than adult skin.' While water alone is insufficient, some cleansers are not appropriate for baby skin. Only cleansers which are clinically proven to be mild and specifically designed for baby skin should be used on baby's sensitive skin.

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