Decades ago, the so-called “hygiene hypothesis” was proposed to explain eczema and related allergic diseases. The hygiene hypothesis suggests that atopic diseases (eczema, asthma, food allergies, and environmental allergies) could be caused if a child grows up in settings that were too clean and sterile. Not being exposed to bacteria, it was thought, impeded proper immune system development.
Over the past 20 years, however, research has shown that the hygiene hypothesis is not necessarily valid. Still, it has raised the idea that a person’s early life experiences may affect their risk to develop eczema and related disorders.
The answer is yes … and no. Eczema does not occur due to proper hygiene, but it may be influenced if a person lacks exposure to healthy bacteria and other organisms. The hygiene hypothesis is discussed frequently in both scientific literature and the media, but the concept of being “too clean” appears to have become misunderstood. The hygiene hypothesis, at its core, is not about a person who is too hygienic. Rather, it is about people who don’t get enough exposure to normal bacteria (and other things in our environments) that make our immune systems stronger.
Personal hygiene and cleaning — hand washing and keeping a clean home, for example — are essential to prevent the spread of infectious diseases, but these do not contribute to a person developing eczema. However, the products we use to keep ourselves and our environments clean may contribute to the condition. Exposure to certain chemicals in soaps and other cleaning products may irritate a person’s skin, disrupt their skin barrier, and contribute to their developing eczema.
The cause of eczema is not fully understood, but its development is known to be influenced by both genetic and environmental factors.
The skin serves as a barrier between our bodies and the outside world. But in a person who has eczema, this barrier has broken down due to a lack of certain proteins. A broken barrier creates an abnormal exposure to the environment. Combined with abnormal immune function, a broken skin barrier can result in immune reactions — and reactions to things that your immune system was never meant to encounter.
Exposure during childhood can result in a person’s immune system becoming sensitized to allergens that are normal parts of our environment. Such exposure can also contribute to a person’s increased risk of developing autoimmune diseases.
Eczema, allergies, and asthma are known as the atopic triad. This triad can occur when a person’s immune system becomes overactive and creates inflammation. The immune system protects the body from disease by recognizing and attacking things that are potentially dangerous, such as viruses and bacteria. It is believed that eczema and related conditions occur when someone’s immune system reads a harmless thing in their body or environment as dangerous. Such an inappropriate immune response can result in chronic, damaging inflammation.
From birth onward, our immune systems learn to recognize what is “safe” and what is “dangerous” through exposure. In addition to what we encounter through our enviroment, we are also exposed to the bacteria and other organisms that live in and on our bodies.
The “old friends hypothesis” has been proposed as a refinement of the hygiene hypothesis. According to the old friends hypothesis, humans (and our immune systems) have evolved to exist in balance with the organisms in our natural microbiome. The microbiome is the collection of bacteria, fungi, and other microorganisms living on our skin and in our gut. These helpful or “good” bacteria are an essential part of having a healthy body and mind. Without exposure to these beneficial bacteria during early childhood, our immune system does not learn that these normal bacteria are safe and mounts an immune response against them.
According to the old friends hypothesis, a healthy microbiome contains a diverse population of different bacteria on the skin and in the gut. Research has shown that people with eczema tend to have an abnormally high ratio of Staphylococcus aureus (a bacteria that causes staph skin infections) to healthy microbes on their skin.
Recently, researchers have found that exposure to nature, including soil and plants, can help restore the diversity needed to have a healthy microbiome. Probiotics may also help maintain a healthy and diverse microbiome. A variety of probiotics containing different species of good bacteria have been proven to help restore a person’s microbiome to normality.
Several environmental factors have been linked to eczema, including exposure to some chemicals.
Antibiotic use during the first year of life has been identified as a risk factor for eczema. Research also shows that if a person takes antibiotics during pregnancy, that can increase the risk of atopic disease in their child. Antibiotics kill not only harmful bacteria, but also some healthy bacteria. This leads to an imbalance of healthy bacteria that is believed to be a risk factor for eczema.
Triclosan is an antibacterial agent. Antibacterial and antimicrobial soaps and detergents containing triclosan do not prevent the spread of bacteria better than plain soap — and they may do more harm than good. Triclosan has been linked to a rise in antibiotic-resistant bacteria. It also is linked to allergies and hay fever through the way it affects your immune system.
Chemical additives, including dyes and fragrances found in soaps and detergents, can trigger eczema. Cleaning agents used at home may also trigger eczema by directly affecting a person’s immune system. Some cleaning agents, as well as chemical additives to foods and soaps, can act as irritants that trigger eczema.
There are several things that you can do to help prevent or control eczema in children, starting with steps a person can take while they are pregnant. Things that may help reduce the risk of childhood eczema and related diseases include:
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