Approximately 15 million Americans suffer from eczema, a chronic condition characterized by dry, red and itchy patches on the skin. As many parents know, it usually begins in infancy. The National Institutes of Health estimates 10%–20% of all infants will develop eczema. Most will see improvement between the ages of 5 and 15, while others must deal with symptoms throughout their lives.
Several foods have historically been known to worsen eczema, including eggs, milk, peanuts, soy, wheat and fish. Some patients report chocolate, coffee, alcohol, tomatoes and sugar can trigger a flare-up, according to Susan C. Taylor, MD, an assistant clinical professor of dermatology at the College of Physicians and Surgeons at Columbia University in New York City. And juices from meats and fruits can irritate already-sensitive skin when they come in contact with it, she says.
New research suggests food allergies are secondary to breaks in the skin’s barrier, says Jon M. Hanifin, MD, a professor of dermatology at Oregon Health and Science University in Portland.
“Dermatologists have suspected for many years that eczema is due to a barrier problem in the skin, as we have seen numerous cases of babies with severe eczema everywhere on their bodies except in the diaper area, which stays surprisingly smooth,” he says. “The reason is that the constant moisture in the diaper area keeps the skin from cracking. That is why we encourage parents to treat eczema in infants as early as possible and continually moisturize the skin.”
Gene mutations are responsible for defects in how the skin’s outer layer develops and functions, and irritants are allowed to penetrate this usually impermeable layer. When food allergens pass through the skin, they produce greater levels of antibodies, which can lead to potentially severe allergic reactions. In fact, 30%–40% of children with severe eczema will develop food allergies from increased antibody levels. As indicated earlier, eggs, peanuts, milk, seafood, soy and wheat pose the greatest threats.
Dr. Hanifin hopes the new research will dispel the common misconception that food allergies cause eczema.
“When kids develop eczema, their parents are desperate to find out what is causing the condition,” he says. “Allergies are an easy, but often mistaken, target. Because of the barrier defect, eczema patients typically have the highest prevalence and the most positive blood or skin tests not only to foods, but to dust mites, pollen and pets. However, these are only tests, and only a small proportion of the tests coincides with an actual allergy. On the other hand, the strong evidence linking a broken skin barrier to the development of future allergies offers an important prevention opportunity. Babies with eczema need early therapy, with measures directed at repair and maintenance of the skin’s barrier.”
In addition to food allergens, irritants from lotions, soaps or fragrances can create problems for eczema patients. When the skin cracks and breaks, irritants pass through it and cause inflammation, stinging or itching. Dr. Hanifin cautions that lotions containing alcohol or other irritants can cause significant irritation to babies with eczema, and he advises parents to apply non-liquid emollients after a bath to moisturize the skin.
Eczema patients with cracked skin are also more susceptible to developing certain bacterial and viral skin infections. The skin is unable to defend itself against microbes, and it flares very quickly, becoming more irritated and itchy. Typically, antibiotics are used to treat the infection, but there are potential consequences.
“Overuse and prolonged treatment with antibiotics are real concerns for dermatologists who treat patients with eczema, as they are at risk for developing antibiotic resistance,” Dr. Hanifin says.
New research will focus on strengthening the skin barrier to prevent and reduce infections.